Orotic Aciduria
Overview Epidemiology Classification Type I: Type II: Etiology Pathophysiology Clinical Presentation Diagnosis Management Differential Diagnosis References:
Purine Salvage Deficiencies
Overview Definition Purines are used for cellular energy and may be recycled through a salvage pathway that is susceptible to enzyme deficiencies that cause Lesch-Nyhan syndrome and adenine phosphoribosyltransferase (APRT) deficiency. Epidemiology Etiology Pathophysiology Lesch-Nyhan syndrome Adenine phosphoribosyltransferase deficiency Clinical Presentation Lesch-Nyhan syndrome Adenine phosphoribosyltransferase deficiency Diagnosis Lesch-Nyhan syndrome Adenine phosphoribosyltransferase deficiency Management Lesch-Nyhan syndrome […]
Nucleic Acids
Overview Definition Nucleic acids are polymers of nucleotides. Main classes: Nucleotide Nucleotides are the basic units of a nucleic acid. Composed of: 5-carbon sugar: Nitrogenous bases: Nucleotides are assembled into nucleic acid polymers by adding 5’–3’ phosphodiester bonds: Naming nucleotides: DNA Overview DNA is the genetic blueprint for life, containing codes for genes. Organization Mitochondrial […]
Niemann-Pick Disease
Overview Classification and etiology Niemann-Pick disease (NPD) is an autosomal recessive lysosomal storage disorder that is classified on the basis of the gene mutation and enzyme deficiency: Epidemiology Pathophysiology Normal lysosomes: In NPD-A and B: In NPD-C: Clinical Presentation The clinical presentation of NPD depends on the type and severity of the disease. Niemann-Pick disease […]
Disorders of Fructose Metabolism
Overview Definition Fructose metabolism is an enzymatic cascade, which causes a breakdown of fructose, a monosaccharide, for energy production. The complex process relies upon a series of enzymes (absent in some individuals) and may cause 3 distinct disorders: essential fructosuria, hereditary fructose intolerance, and intestinal fructose intolerance. Normal fructolysis Fructolysis is the 1st portion of […]
Metachromatic Leukodystrophy
Overview Definition Metachromatic leukodystrophy (MLD) is an autosomal recessive white matter disease caused by a deficiency in arylsulfatase A resulting in accumulation of cerebroside sulfate. This accumulation leads to the destruction of myelin and causes neurologic deficits. Classification Based on age at symptom onset: Epidemiology Etiology Pathophysiology Clinical Presentation Late infantile form Juvenile form Adult […]
Stages of Transcription
Overview of Gene Expression Definition Central dogma: To express a gene, DNA is transcribed into RNA, which is then translated into a protein (or a protein fragment known as a polypeptide). Transcription is the process by which DNA is used as a template to make mRNA. DNA DNA is a double-helix molecule made up of […]
Post-translational Protein Processing
Amino Acid Overview Amino acids are the building blocks of proteins. Understanding the basics of amino acids allows a more comprehensive understanding of protein folding and modification. Amino acid structure Amino acids that make up proteins are known as α-amino acids. Each of these amino acids has a central carbon known as the “alpha carbon,” […]
Stages and Regulation of Translation
Central Dogma and Genetic Code Definition DNA RNA The genetic code The genetic code is how organisms translate a sequence of bases into an actual protein. Components of Translation mRNAs are translated into proteins by the ribosomes and transfer RNAs. Transfer RNAs (tRNAs) tRNAs carry amino acids to the ribosomes, where they bind to the […]
Epigenetic Regulation
Overview Definition Epigenetic modification are modifications to the DNA or DNA packaging that affect gene expression without altering the genetic code (i.e., sequence of DNA) itself. These modifications: Overview of epigenetic regulation Review of DNA packaging in chromatin The basic unit of DNA packaging is the nucleosome. DNA wraps 2¼ times around a core of […]