HIGH-INCIDENCE OF CENTRAL-NERVOUS-SYSTEM MALFORMATIONS ASSOCIATED WITH MARKED PARENTAL CONSANGUINITY IN AN ISRAELI ARAB COMMUNITY

It is common among Israeli Arabs who live in villages to prefer consan guineous marriages, particularly among first cousins. In addition, suc h villages are populated by a few (< 20) original families, and inter- family/inter-village marriages are infrequent. The purpose of this stu dy was to examine the incidence of congenital malformation of the cent ral nervous system associated with such ''consanguinity'' in Taibe, a large Arab village, 30 km from Tel Aviv. Six hundred and ten families were prospectively ascertained through infants who were routinely seen in the local ''Well Baby Clinics''. A significant increase in the inc idence of major malformations was noted in relation to the closeness o f the parental relationship. For the index cases group, the prevalence of individuals with major malformations was 5.8% in the product of in ter-village marriages, 8.3% in the intra-village non-related matings, 15.1% in the distant consanguineous group, and up to 15.8% in the prog eny of first-cousin marriages (P < 0.001). Malformations of the centra l nervous system consisted of 1/3 to 1/2 of the total malformations in the consanguineous groups versus less than 1/5 in the non-consanguine ous groups. The study demonstrates a marked high rate of consanguineou s marriages, the effect of which leads to a marked increase in major m alformations and especially those of the central nervous system. This requires a unique genetic counseling approach.