Relative RiskComments
parentGenetic disease
siblingsAndrogen InsensitivityBalanced RearrangementCancer geneticsChromosome Number AbnormalitiesCystic FibrosisDown SyndromeDuchenne Muscular DystrophyFragile X SyndromeHemoglobinopathyHuntington DiseaseHurler SyndromeHyperphenylalaninemiamRNA Splicing AberrationsNondisjunctionPenis-At-Twelve SyndromeSickle Cell DiseaseSpinal Muscular AtrophyTay-Sachs DiseaseThalassemiaTriplet Repeat ExpansionsTrisomy 13Trisomy 18Unbalanced RearrangementUniparental Disomy

Relative Risk

λr = (prevalence of disease in relatives of an affected person) / (prevalence of disease in the general population)

Relative Risk (λr) is one measure (along with case-control studies) for measuring familial aggregation. Familial aggregation (clustering of a disease within a family) is a characteristic of diseases with complex inheritance. λr can be adapted for siblings (λr=s) or parents (λr=p).