The Numbers of Aunts and Uncles of Normal and Congenitally Abnormal Children

Summary Published muscular dystrophy pedigrees showed asymmetries in the numbers of maternal and paternal aunts and uncles. The question arose of the numbers which should be expected for normal children and it was deduced that symmetry was a reasonable expectation. This was confirmed in a sample of normal children. The analysis was then extended to the families of propositi with other congenital abnormalities, mongolism, exomphalos, congenital heart disease, patent ductus arteriosus and infantile pyloric stenosis. Other asymmetries of numbers were found with respect to the sex of the propositus, of the parent, and of the parents' sibs. It was concluded that at least some of these findings were related to the factors determining the occurrence of the abnormalities.