ABSTRACT
The study comprised 29 patients with features suggestive of phakomatoses refered to the Human Genetic Clinic, Medical Research Institute, and Dermatology Department, Faculty of Medicine, Alexandria University. All the patients were subjected to complete genetic history, pedigree analysis, clinical genetic, dermatological examinations, radiological investigations [X-ray, Ultrasonography and CT] and cytogenetic study in some patients. The result revealed that: 19 patients had neurofibromatosis [NF], 17 had NF I, one patient had Cafe au-lait type and the last one had segmental type. NF is the most common type of phakomatoses and is inherited as autosomal dominant. Eight patients had chromosomal instability syndromes [4 had xeroderma pigmentoza, 2 had De Sanctis Cacchione syndrome and 2 had ataxia telangiectasia]. Increased chromosomal breaks among these patients were detected by special technique. Chromosomal instability syndromes are inherited as autosomal recessive. The last 2 female patients were diagnosed as focal dermal hypoplasia syndrome [FDH] which is an X-linked dominant phakomatoses. In phakomatoses regular follow up examination and genetic counseling with emphasis on new symptoms are necessary to allow early intervention, detection of