Chapter Summary continued

Von Hippel-Lindau disease is due to an abnormality of a tumor suppressor gene of chromosome 3p and is characterized clinically by hemangioblastomas in the central nervous system and retina, renal-cell carcinoma, and cysts of internal organs.

Fragile X syndrome is an important cause of familial mental retardation and is due to a triple nudeotide repeat mutation in the FMR-I gene on the X chromosome. It is characterized clinically by mental retardation (affected males more severe than female earners), elongated face, large ears, and macro-orchidism.

Huntington disease is due to a triple repeat mutation of the Huntington gene, which clinically produces atrophy of the caudate nucleus with choreiform movements and progressive dementia.

Genomic imprinting refers to differential expression of genes based on chromosomal inheritance from maternal versus paternal origin. The classic examples are the mental retardation syndromes Prader-Willi syndrome (paternal deletion of chromosome 15 with obesity and hypogonadism) and Angelman syndrome (maternal deletion of chromosome 15 producing ataxia and inappropriate laughter characterized as "happy puppet").

0 0

Post a comment