Trisomy 7 mosaicism associated with carbohydrate-deficient glycoprotein syndrome and incontinentia pigmenti phenotype. R. Jayoussi1, R. Brill1, H. Mandel1,2, O. Lobel1, I. Laeveski1, Z. Galperin1, R. Gershoni-Baruch1,2. 1) Human Genetics, Rambam Medical Ctr, Haifa, Israel; 2) The Bruce Rappaport Faculty of Medicine, Technion, Institute of Technology, Haifa, Israel.
A girl with dysmorphic features, severe mental retardation and anomalous skin pigmentation associated with trisomy 7 and an unusual pattern of carbohydrate glycoprotein deficiency is described. Born at term to young, unrelated couple of Jewish Ashkenazi origin, following normal gestation and delivery. Birth weight was 2650g. (< 3rd centile) and OFC 34cm. (3rd centile). At two years of age she was referred for investigation because of slow psychomotor development. On clinical examination the following features were noted: high forehead, antimongolian slant, deep set eyes, a depressed nasal bridge, dysplastic low set ears, widely spaced inverted nipples, widespread irregular streaks and punctate lesions of depigmentation on trunk and all four limbs. Her lymphocyte karyotype was normal and she was given the diagnosis of incontinentia pigmenti. Anomalous pigmentation known to be correlated to chromosomal mosaicism or chimerism induced further evaluation and a skin fibroblast which was performed showed trisomy 7 mosaicism (46,XX/47,XX+7). FISH using a centromeric direct probe (Cytocell) confirmed the diagnosis. Extensive biochemical evaluation revealed an abnormal serum transferrin isoelectro-focusing pattern, consisting of an increased amount of disialotransferrin, reduced amounts of tetra, penta and hexasialotransferrin and a small amount of monosialotransferrin. Normal phosphomanomutase and phosphomanose isomerase activities in fibroblasts are consistent with the diagnosis of a previously undescribed variant of a carbohydrate-deficient glycoprotein syndrome. The association of the clinical biochemical and chromosomal abnormalities remains to be defined and clarified.