Autosomal trisomy 18 and 13 syndromes in Ibadan, Nigeria.

The clinical, cytogenetic, dermatoglyphic and autopsy findings in 14 cases of trisomy 18 as well as in seven cases of trisomy 13 seen in the Paediatric Department of University College Hospital (UCH), Ibadan, Nigeria, from 1972 to 1981 are presented. The incidence was 0.12 and 0.08 per 1000 livebirths for trisomies 18 and 13 respectively. All the patients were of regular trisomies except two; one case was mosaic for trisomy 18 and another case of trisomy 13 seemed to have derived an extra chromosome of the D group from a reciprocal D/D translocation that was maternally carried. Both syndromes have certain physical features in common which sometimes made clinical diagnosis difficult, but each had diagnostic features of its own. While the combination of microcephaly, cleft lip and/or palate, microphthalmos, capillary haemangioma and polydactyly form the hallmark of trisomy 13, the presence of prominent occipit, micrognathia, clenched fist together with protruding heel make the appearance of trisomy 18 unmistakable. The prognosis in both syndromes is poor and those who survive beyond infancy exhibit severe mental retardation. It is therefore important to establish the diagnosis early so as to conserve limited resources in an attempt to prolong the lives of neonates with these syndromes.