Inheritance of microtia in the Finnish population.

Objective: To study the inheritance of microtia in the Finnish population, identify families for genetic linkage analyses and compare the phenotype between sporadic and familial patients.
Methods: Retrospective case series and patient questionnaire of 109 microtia patients referred for reconstruction of the earlobe to the Helsinki University Central Hospital during the years 1980-2005.
Results: 22 out of the 109 patients had a relative with microtia or preauricular tag. The familial and sporadic patients did not differ in microtia phenotype or sex distribution. Urinary system anomalies were statistically more prevalent in familial patients (p<0.01). The analyses of the birthplace of parents or grandparents of familial or sporadic microtia patients resulted in no evidence for founder effect.
Conclusions: The prevalence of familial microtia/OAVS in the Finnish population is higher than 20%. The sporadic and familial microtia/OAVS patients do not differ in the phenotype or sex distribution. The mode of inheritance seems to be autosomal dominant with incomplete penetrance.