Human genome--chromosome no. 19

Chromosome 19 is short but has higher relative density of genes than other chromosomes. Increasing number of the genes coding for proteins implicated in the pathogenesis of various human diseases have been mapped on chromosome 19. Mutations of low density lipoprotein receptor (LDL-R) result in one of the most frequent mendelian inherited disorder-familial hypercholesterolemia. Mutations of insulin receptor (INSR) are causative for rare syndromes of insulin resistance and some of non insulin dependent diabetes mellitus (NIDDM). Erythropoietin receptor (EPOR) mutations are causative for rare primary familial and congenital polycythemias (PFCP). Defects of one of the largest gene in the human genome RYR 1 (ryanodine receptor gene) (> 240 kb in size) accounts for majority of malignant hyperthermia (MH) and central core disease (CCD). All these disorders represent group of receptor diseases. The amplification of GCT trinucleotide repeats in myotonic dystrophy protein kinase (DMPK) gene is causative for myotonic dystrophy (DM) and represents a new class of human gene mutations: trinucleotide repeat mutations. Apolipoprotein E (APOE) locus plays a role in pathogenesis of the late onset familial Alzheimer's disease. Translocation of EA2 gene which encodes two helix-loop-helix (HLH) transcription proteins and its fusion with PBXI or hepatic leukemia factor (HLF) leads to the leukemogenesis in subgroup of ALL. Interestingly adeno-associated virus (AAV), currently widely used as vector for gene therapy has unique capability of specific integration into human chromosome 19q.