ABSTRACT
Thirty four cases presenting with isolated microcephaly were ascertained from the outpatient clinic of Human Genetics Department [HGD], The National Research Center [NRC] in the last 2 years. Eight cases were familial in 4 families, [2 affected sibs in each], and 26 sporadic cases. Positive consanguinity was found in 64% of all the cases. It was possible to classify our cases according to their etiology into the following: [1] Genetic causes: a- Microcephaly with spastic paraplegia and or quadriplegia: 16 cases [6 familial and 10 sporadic]. b- Microcephaly with eye manifestations [optic atrophy or chorioretinopathy] 6 sporadic cases. c- Metabolic causes [3 cases, 2 familial and 1 sporadic]. 2] Enviromental causes in 9 cases [all sporadic]. This study emphasizes the etiologic heterogeneity of isolated microcephaly, the preponderance of autosomal recessive forms and that consanguinity plays a major role in its etiology in our society