MEDI7212 Lecture 55: W8 - Medical genetics
Document Summary
Overview: a gene is the basic unit of heredity comprised of a dna segment that makes up a chromosome containing all information necessary to synthesize a polypeptide (protein) Structure: humans have 20,000-23,000 genes comprised of dna -> dna is wound around an octamer of core histone proteins forming chromatin/ chromosomes -> chromosomes are found in cell nucleus & mitochondria. Single gene (mendelian) - point mutations, deletions or duplications, triplet expansion: chromosomal - aneuploidy, deletions or duplications, mosaicism, mitochondrial - mtdna, nuclear genes, multifactorial. Spontaneous or cellular insult-induced (drug, radiation) dna variation passed onto subsequent cells without dna repair: polymorphism. Spinocerebellar ataxia: myotonic dystrophy, osteogenesis imperfecta, ad pkd, achondroplasia. Sickle cell disease: phenylketonuria, glycogen storage disease, cah, haemochromatosis. It can depend on sex of transmitting parent (hd for male, myotonic dystrophy for female: examples - myotonic dystrophy, fragile x syndrome, huntington disease, extra or missing chromosomes. Abnormal autosome number: trisomy 21 (downs, trisomy 18 (edward, trisomy 13 (patau)
