Medical Genetics B. In the extremely rare instances where two affected individuals have mated the homozygous affected individuals usually are so severely affected they are not compatible with life. The exceptions are the autosomal dominant diseases caused by the somatic expansion of trinucleotide repeat sequences (e.g. Huntington 's disease that we will study later
Medical Genetics B. In the extremely rare instances where two affected individuals have mated, the homozygous affected individuals usually are so severely affected they are not compatible with life. The exceptions are the autosomal dominant diseases caused by the somatic expansion of trinucleotide repeat sequences (e.g., Huntington's disease) that we will study later
Medical Genetics C. The mating of very closely related individuals, the most likely way for two affected individuals to know each other, is forbidden in our society
Medical Genetics C. The mating of very closely related individuals, the most likely way for two affected individuals to know each other, is forbidden in our society
Medical Genetics With the understanding that almost all affected individuals are heterozygotes, and that in most matings involving a person with an autosomal dominant trait the other partner will be homozygous normal there are four hallmarks of autosomal dominant inheritance
Medical Genetics With the understanding that almost all affected individuals are heterozygotes, and that in most matings involving a person with an autosomal dominant trait the other partner will be homozygous normal, there are four hallmarks of autosomal dominant inheritance
Medical Genetics There are four hallmarks of autosomal dominant inheritance (1)Except for new mutations, which are rare in nature and extremely rare on examination pedigrees, and the complexities of incomplete penetrance to be discussed later, every affected individual has an affected biological parent. There is no skipping of generations. (2) Males and females have an equally likely chance of inheriting the mutant allele and being affected. The recurrence risk of each child of an affected parent is
Medical Genetics There are four hallmarks of autosomal dominant inheritance: (1) Except for new mutations, which are rare in nature and extremely rare on examination pedigrees, and the complexities of incomplete penetrance to be discussed later, every affected individual has an affected biological parent. There is no skipping of generations. (2) Males and females have an equally likely chance of inheriting the mutant allele and being affected. The recurrence risk of each child of an affected parent is 1/2
Medical Genetics (3) Normal siblings of affected individuals do not transmit the trait to their offspring. (4)The defective product of the gene is usually a structural protein, not an enzyme. Structural proteins are usually defective when one of the allelic products is nonfunctional enzymes usually require both allelic products to be nonfunctional to produce a mutant phenotype
Medical Genetics (3) Normal siblings of affected individuals do not transmit the trait to their offspring. (4)The defective product of the gene is usually a structural protein, not an enzyme. Structural proteins are usually defective when one of the allelic products is nonfunctional; enzymes usually require both allelic products to be nonfunctional to produce a mutant phenotype