Effects on Inheritance Patterns
Figure 7-19 Pedigree of a family with paraganglioma syndrome 1 caused by a mutation in the SDHD gene. Individuals II-1, II-2, II-4, III-2, III-3, III-9, III-10, IV-6, IV-7, IV-11, and IV-14 each inherited the mutation from their mothers but are unaffected. However, when the males in this group pass on the mutation, those children can be affected. In addition to the imprinting, the family also demonstrates the effect of reduced and age-dependent penetrance in the children (III-6, IV-10, IV-17) of heterozygous fathers. The + and − symbols refer to the presence or absence of the SDHD mutation in this family.