16VarMendel - the result of the high frequency of the TSD...

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Pedigrees Basic pedigrees autosomal recessive autosomal dominant X-linked recessive Y-linked sex-influenced Conditional probability p (affected) from 1 x 2 p (affected) from 1 x 3 Variations on Mendel’s Theme lethal allele incomplete dominance codominance complementation epistasis multiple alleles compound heterozygote (from OMIM entry #272800. At http://www.ncbi.nlm.nih.gov choose OMIM and search.) In Israel, Navon et al. (1986) identified 18 Hex-A-deficient adults by the end of 1985. All were Ashkenazi. The clinical picture varied between and within families and included spinocerebellar, various motor neuron, and cerebellar syndromes. The possibility exists that many of the affected persons are compound heterozygotes of the TSD allele with another rare allele. The relatively high frequency of the atypical adult disorder(s) in Ashkenazim is
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Unformatted text preview: the result of the high frequency of the TSD allele to create genetic compounds. pleiotropy (from OMIM entry #310200) The most distinctive feature of Duchenne muscular dystrophy is a progressive proximal muscular dystrophy with characteristic pseudohypertrophy of the calves. The onset of Duchenne muscular dystrophy usually occurs before age 3 years, and the victim is chairridden by age 12 and dead by age 20. ... Mental retardation of mild degree is a pleiotropic effect of the Duchenne gene (Zellweger and Niedermeyer, 1965). variable expressivity penetrance (from OMIM entry #113705): The penetrance of the BRCA1 gene was estimated to be 0.92 by age 70. 25 1 3 2 4 8 1 2 3 5 6 7...
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