DiGeorge Syndrome

Epidemiology and Etiology

Epidemiology

• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: 1 in 4,000–7,000 live births
• Most common human chromosomal microdeletion syndrome
• Growing prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency due to the following factors:
  • Surgical correction of cardiac defects improves the survival rate of affected patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship, thus increasing their likelihood of passing on the condition.
  • Parents who were previously unaware of their genetic condition are being diagnosed as genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies becomes more available.
  • Earlier genetic techniques were not able to detect all deletions; newer technologies also cover atypical deletions.

Etiology

• Synonyms:
  • Velocardiofacial syndrome
  • Shprintzen syndrome
  • Conotruncal anomaly face syndrome (CTAF)
  • Takao syndrome
• Caused by a heterozygous deletion of part of the long arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy (q) of chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 22, region 1, band 1, sub-band 2 (22q11.2)
• The deletion of 22q11.2 is 10 times more common than the next most frequent deletion syndrome, suggesting that this region is inherently unstable.
• 93% of cases are de novo mutations during early fetal development.
• 7% of cases are inherited in autosomal dominant Autosomal dominant Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal dominant diseases are expressed when only 1 copy of the dominant allele is inherited. Autosomal Recessive and Autosomal Dominant Inheritance patterns from affected parents.

Pathophysiology

• Approximately 30–50 genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure are affected by the 22q11.2 deletion.
  • Disrupts the development of the 3rd and 4th pharyngeal pouches Pharyngeal pouches Branchial Apparatus and Aortic Arches
  • Creates a defect in the embryonic development of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification, neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess, skeleton, and kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy
• TBX1 is the main gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics responsible for the DiGeorge phenotype Phenotype The complete genetic complement contained in the DNA of a set of chromosomes in a human. The length of the human genome is about 3 billion base pairs. Basic Terms of Genetics. It plays a vital role in organ formation and regulation, affecting the formation of:
  • Skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy bones
  • Mesenchyme of the face and palate Palate The palate is the structure that forms the roof of the mouth and floor of the nasal cavity. This structure is divided into soft and hard palates. Palate: Anatomy
  • Outflow tract of the heart
  • Thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy and parathyroid Parathyroid The parathyroid glands are 2 pairs of small endocrine glands found in close proximity to the thyroid gland. The superior parathyroid glands are lodged within the parenchyma of the upper poles of the right and left thyroid lobes; the inferior parathyroid glands are close to the inferior tips or poles of the lobes. Parathyroid Glands: Anatomy stroma 
• 22q11.2 deletions are associated with a higher risk of early onset Parkinson’s disease.

Clinical Presentation

DiGeorge syndrome has a marked variability in clinical expression among different individuals. Manifestations can include the following:

• Congenital cardiovascular disease:
  • Interrupted aortic arch Aortic arch Mediastinum and Great Vessels: Anatomy 
  • Patent truncus arteriosus Truncus arteriosus Truncus arteriosus (TA) is a congenital heart defect characterized by the persistence of a common cardiac arterial trunk tract that fails to divide into the pulmonary artery and aorta during embryonic development. Truncus arteriosus is a rare congenital malformation with a high mortality rate within the 1st 5 weeks of life if not managed promptly. Truncus Arteriosus 
  • Tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. Tetralogy of Fallot
  • Atrial or ventricular septal defect Ventricular Septal Defect Tetralogy of Fallot 
  • Vascular rings Vascular Rings Pediatric Vomiting (causing tracheal or esophageal compression Compression Blunt Chest Trauma)
• Abnormal craniofacial features:
  • Hypertelorism
  • Tubular nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal)
  • Hooded eyes
  • Cleft palate Cleft palate Congenital fissure of the soft and/or hard palate, due to faulty fusion. Cleft Lip and Cleft Palate
  • Low-set or posteriorly rotated ears
• Endocrine issues:
  • Hypoparathyroidism Hypoparathyroidism Hypoparathyroidism is defined as reduced parathyroid hormone (PTH) levels due to poor function of the parathyroid glands. The cause of hypoparathyroidism is most commonly iatrogenic following neck surgery, but it can also be associated with genetic or autoimmune disorders as well as infiltrative diseases causing destruction of the normal parathyroid tissue. Hypoparathyroidism (50% of cases; causes hypocalcemia Hypocalcemia Hypocalcemia, a serum calcium < 8.5 mg/dL, can result from various conditions. The causes may include hypoparathyroidism, drugs, disorders leading to vitamin D deficiency, and more. Calcium levels are regulated and affected by different elements such as dietary intake, parathyroid hormone (PTH), vitamin D, pH, and albumin. Presentation can range from an asymptomatic (mild deficiency) to a life-threatening condition (acute, significant deficiency). Hypocalcemia, which can lead to seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures)
  • Growth hormone deficiency
• Thymic aplasia Aplasia Cranial Nerve Palsies/ hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) (leads to immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome due to reduced T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions):
  • Complete DiGeorge syndrome:
    • Only 1% of cases
    • Thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy is completely absent
    • Causes severe combined immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome ( SCID SCID Severe combined immunodeficiency (SCID), also called “bubble boy disease,” is a rare genetic disorder in which the development of functional B and T cells is disturbed due to several genetic mutations that result in reduced or absent immune function. Severe Combined Immunodeficiency (SCID)); manifests as recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID), chronic diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, and failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive
    • Fatal unless promptly treated
  • Partial DiGeorge syndrome:
    • Range of normal to deficient T cell numbers 
    • Approximately 75% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with thymic defect
    • Varying degree of immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome, although a normal number of T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions may be reached by adulthood (proliferation of existing T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions)
    • Associated with humoral immunodeficiencies of immunoglobulin A ( IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions) deficiency
• Neurological problems:
  • Learning disabilities (up to 90% of cases), speech delay
  • High risk of early onset Parkinson’s disease
  • Conductive and sensorineural hearing loss Sensorineural hearing loss Hearing loss resulting from damage to the cochlea and the sensorineural elements which lie internally beyond the oval and round windows. These elements include the auditory nerve and its connections in the brainstem. Hearing Loss 
• Psychiatric disorders: 
  • Depression, bipolar Bipolar Nervous System: Histology disorder
  • Attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment deficit hyperactivity Hyperactivity Attention Deficit Hyperactivity Disorder disorder ( ADHD ADHD Attention deficit hyperactivity disorder is a neurodevelopmental disorder characterized by a pattern of inattention and/or hyperactivity-impulsivity that occurs in at least 2 different settings for more than 6 months. Although the patient has normal intelligence, the disease causes functional decline. Attention Deficit Hyperactivity Disorder)
  • Schizophrenia Schizophrenia Schizophrenia is a chronic mental health disorder characterized by the presence of psychotic symptoms such as delusions or hallucinations. The signs and symptoms of schizophrenia are traditionally separated into 2 groups: positive (delusions, hallucinations, and disorganized speech or behavior) and negative (flat affect, avolition, anhedonia, poor attention, and alogia). Schizophrenia
• Miscellaneous:
  • Laryngotracheoesophageal defects
  • Digestive motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility issues
  • Skeletal abnormalities
  • Anomalies of the genitourinary and respiratory tract
  • Autoimmune diseases Autoimmune diseases Disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides. Selective IgA Deficiency (e.g., Graves’ disease and rheumatoid arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis)

Mnemonic

DiGeorge syndrome signs can be summarized using the mnemonic CATCH-22:

• C: Congenital heart disease
• A: Abnormal facies
• T: Thymic aplasia Aplasia Cranial Nerve Palsies
• C: Cleft palate Palate The palate is the structure that forms the roof of the mouth and floor of the nasal cavity. This structure is divided into soft and hard palates. Palate: Anatomy
• H: Hypocalcemia/hypoparathyroidism
• 22: 22q11.2DS, found on chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 22

Diagnosis and Management

Diagnosis

Establishing a diagnosis is difficult due to the variability of phenotypes. A diagnosis of DiGeorge is determined by demonstrating a decrease in CD3 CD3 Complex of at least five membrane-bound polypeptides in mature T-lymphocytes that are non-covalently associated with one another and with the T-cell receptor. The CD3 complex includes the gamma, delta, epsilon, zeta, and eta chains (subunits). When antigen binds to the T-cell receptor, the CD3 complex transduces the activating signals to the cytoplasm of the T-cell. The CD3 gamma and delta chains (subunits) are separate from and not related to the gamma/delta chains of the T-cell receptor. T cells: Types and Functions+ T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions in addition to characteristic clinical findings and genetic studies demonstrating deletion in chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics area 22q11.2.

• Genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies—array comparative genomic hybridization Hybridization The genetic process of crossbreeding between genetically dissimilar parents to produce a hybrid. Blotting Techniques (aCGH):
  • Preferred test
  • Detects deletions or duplications
• Lab work and imaging to identify associated defects:
  • Cardiology:
    • Electrocardiogram Electrocardiogram An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) ( ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG))
    • Echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA)
  • Endocrine:
    • Serum calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes and phosphorus levels (↓ PTH, ↓ calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes, ↑ phosphorus)
    • Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy profile test
    • Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests (to check absence of thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy)
  • Immune function tests:
    • CBC to evaluate for lymphopenia, immunoglobulin levels Immunoglobulin levels Wiskott-Aldrich Syndrome, T- and B-cell subsets
    • Renal ultrasound (look for structural genitourinary tract abnormalities)

Management

Management is aimed at treating the associated features of the disease. Early intervention and developmental evaluation are key.

• Thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy transplantation or hematopoietic cell transplantation (HCT)
• Antibiotics (for treating frequent infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease), IV immunoglobulins Immunoglobulins Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions 
• Cautionary use of blood transfusions Blood transfusions The introduction of whole blood or blood component directly into the bloodstream. Transfusion Products and live attenuated vaccines
• Cardiac surgery Cardiac surgery Cardiac surgery is the surgical management of cardiac abnormalities and of the great vessels of the thorax. In general terms, surgical intervention of the heart is performed to directly restore adequate pump function, correct inherent structural issues, and reestablish proper blood supply via the coronary circulation. Cardiac Surgery to correct congenital heart abnormalities
• Correction of palatal defects
• Lifelong vitamin D Vitamin D A vitamin that includes both cholecalciferols and ergocalciferols, which have the common effect of preventing or curing rickets in animals. It can also be viewed as a hormone since it can be formed in skin by action of ultraviolet rays upon the precursors, 7-dehydrocholesterol and ergosterol, and acts on vitamin D receptors to regulate calcium in opposition to parathyroid hormone. Fat-soluble Vitamins and their Deficiencies and calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes supplementation
• Genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies and counseling for parents considering having other children

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

There is no cure for DiGeorge syndrome. Life expectancy Life expectancy Based on known statistical data, the number of years which any person of a given age may reasonably expected to live. Population Pyramids largely depends on the degree of cardiac defects (most important factor) and immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome.

• Complete DiGeorge syndrome:
  • Without transplantation, the life expectancy Life expectancy Based on known statistical data, the number of years which any person of a given age may reasonably expected to live. Population Pyramids of infants is < 1 year.
  • In patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who undergo a transplant, most deaths occur in the first year post-transplant.
  • Majority of deaths attributed to cardiac complications
• Partial DiGeorge syndrome: prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas dependent on severity of cardiac defect, patient’s intellectual development, and follow-up care provided for their associated deficiencies

Differential Diagnosis

• CHARGE Syndrome CHARGE Syndrome CHARGE syndrome is a rare genetic condition with autosomal dominant inheritance in which almost all body systems are affected. The acronym CHARGE stands for the constellation of clinical features seen with this condition: Coloboma, Heart defects, Atresia choanae, Growth retardation, Genetic Abnormalities, and Ear abnormalities. CHARGE Syndrome: a rare genetic condition with autosomal dominant inheritance Autosomal dominant inheritance Autosomal Recessive and Autosomal Dominant Inheritance. The abbreviation CHARGE stands for the constellation of clinical features seen with this condition: coloboma Coloboma Congenital anomaly in which some of the structures of the eye are absent due to incomplete fusion of the fetal intraocular fissure during gestation. Esophageal Atresia and Tracheoesophageal Fistula, heart defects, choanal atresia Atresia Hypoplastic Left Heart Syndrome (HLHS), growth retardation Growth Retardation Failure of a fetus to attain expected growth. Fetal Alcohol Spectrum Disorder, genetic abnormalities, and ear abnormalities. Like, DGS, cardiac defects, cleft palate Cleft palate Congenital fissure of the soft and/or hard palate, due to faulty fusion. Cleft Lip and Cleft Palate and hearing loss Hearing loss Hearing loss, also known as hearing impairment, is any degree of impairment in the ability to apprehend sound as determined by audiometry to be below normal hearing thresholds. Clinical presentation may occur at birth or as a gradual loss of hearing with age, including a short-term or sudden loss at any point. Hearing Loss are present but the other features listed are not seen in DGS. Genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies confirms the diagnosis. There is no 22q11 deletion in CHARGE syndrome CHARGE Syndrome CHARGE syndrome is a rare genetic condition with autosomal dominant inheritance in which almost all body systems are affected. The acronym CHARGE stands for the constellation of clinical features seen with this condition: Coloboma, Heart defects, Atresia choanae, Growth retardation, Genetic Abnormalities, and Ear abnormalities. CHARGE Syndrome. Treatment is symptomatic with management of the airway Airway ABCDE Assessment, heart defects, and feeding ability as the priorities in early life. 
• Zellweger syndrome Zellweger syndrome Zellweger syndrome (ZWS), also called cerebrohepatorenal syndrome, is a rare congenital peroxisome biosynthesis disorder and is considered an inborn error of metabolism. Zellweger syndrome is the most severe form of a spectrum of conditions called Zellweger spectrum disorder (ZSD), and is characterized by the reduction or absence of functional peroxisomes. Zellweger Syndrome ( ZWS ZWS Zellweger syndrome (ZWS), also called cerebrohepatorenal syndrome, is a rare congenital peroxisome biosynthesis disorder and is considered an inborn error of metabolism. Zellweger syndrome is the most severe form of a spectrum of conditions called Zellweger spectrum disorder (ZSD), and is characterized by the reduction or absence of functional peroxisomes. Zellweger Syndrome), also called cerebrohepatorenal syndrome Cerebrohepatorenal syndrome Zellweger syndrome (ZWS), also called cerebrohepatorenal syndrome, is a rare congenital peroxisome biosynthesis disorder and is considered an inborn error of metabolism. Zellweger syndrome is the most severe form of a spectrum of conditions called Zellweger spectrum disorder (ZSD), and is characterized by the reduction or absence of functional peroxisomes. Zellweger Syndrome, is a rare congenital peroxisome biosynthesis Biosynthesis The biosynthesis of peptides and proteins on ribosomes, directed by messenger RNA, via transfer RNA that is charged with standard proteinogenic amino acids. Virology disorder and is considered an inborn error Error Refers to any act of commission (doing something wrong) or omission (failing to do something right) that exposes patients to potentially hazardous situations. Disclosure of Information of metabolism. It is the most severe form of a spectrum of conditions called Zellweger spectrum disorders ( ZSD ZSD Zellweger Syndrome). It is characterized by the reduction or absence of functional peroxisomes Peroxisomes Microbodies which occur in animal and plant cells and in certain fungi and protozoa. They contain peroxidase, catalase, and allied enzymes. The Cell: Organelles. Symptoms are present from the time of birth and include hypotonia Hypotonia Duchenne Muscular Dystrophy, poor feeding, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures. Like DGS, there is craniofacial dysmorphism. But DGS does not typically have hepatomegaly with cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis. There is no cure for Zellweger syndrome Zellweger syndrome Zellweger syndrome (ZWS), also called cerebrohepatorenal syndrome, is a rare congenital peroxisome biosynthesis disorder and is considered an inborn error of metabolism. Zellweger syndrome is the most severe form of a spectrum of conditions called Zellweger spectrum disorder (ZSD), and is characterized by the reduction or absence of functional peroxisomes. Zellweger Syndrome. 
• Teratogen exposure: teratogens Teratogens An agent that causes the production of physical defects in the developing embryo. Cleft Lip and Cleft Palate such as isotretinoin, ethanol Ethanol A clear, colorless liquid rapidly absorbed from the gastrointestinal tract and distributed throughout the body. It has bactericidal activity and is used often as a topical disinfectant. It is widely used as a solvent and preservative in pharmaceutical preparations as well as serving as the primary ingredient in alcoholic beverages. Ethanol Metabolism or maternal conditions such as diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus affect the fetus in utero and produce similar phenotype Phenotype The complete genetic complement contained in the DNA of a set of chromosomes in a human. The length of the human genome is about 3 billion base pairs. Basic Terms of Genetics as DGS. The difference is genetic abnormality is present in DGS. Additionally, the abnormalities depend on the development period during which there was exposure.