Genetic study of microcephaly; syndromal and non syndromal

ABSTRACT

This study included 100 patients suffering from microcephaly, from those attending the Genetic Clinic, Medical Research Institute, Alexandria University. They were subjected to complete genetic, family, pregnancy and delivery history, pedigree analysis, anthropometric measurements, clinical genetic examination, chromosomal analysis, X-rays and other investigations [CT, ophthalmological examination, EEG]. The results revealed that 38 patients had non syndromal microcephaly [52.6% isolated cases and 47.4% familial]. The estimated sib recurrence risk for isolated microcephaly was 20%. Several varieties of autosomal recessive microcephaly were found with a high frequency of microcephaly with seizures and spasticity [50% and 44% in isolated and familial cases respectively]. Syndromal microcephaly included 62 patients. Out of these, 40 had single gene disorders 14 [35%] had autosomal dominant syndromes, 22 [55%] had autosomal recessive and 4 [10%] had X-linked recessive [XLR] syndromes. Seventeen patients had chromosomal abnormalities with 70.5% due to numerical aberrations and 29.5% had structural defects. Four patients were microcephalic due to environmental exposure to infections and one secondary to craniosynostosis. The high frequency of consanguinity [72%] and estimated sib recurrence risk reflect the high contribution of autosomal recessive microcephaly and syndromes in this study