Eleven patients with the so-called Cat Eye syndrome are reported including a more detailed description of the original cases reported by Schmid and Fraccaro. All cases had, in addition to a normal karyotype, a small extra G-like chromosome which appeared to be an isochromosome for the juxtacentromeric region (pter to q11) of an acrocentric chromosome. None were mosaics. Clinical findings and further cytogenetic studies in a few cases suggest that these markers probably derive from a No. 22 chromosome. Characteristic features of the Cat Eye syndrome in these 11 patients and those reviewed from the literature are: ocular coloboma which may involve the iris, choroid and/or optic nerve, preauricular skin tags and/or pits which are probably the most consistent feature, congenital heart defect, anal atresia with a fistula, renal malformations such as unilateral absence, unilateral or bilateral hypoplasia, and cystic dysplasia, and antimongoloid position of eyes. Intelligence is usually low-normal, although moderate retardation is also seen. There is great variability in the clinical findings ranging from near normal to lethal malformations. Less frequent, but also characteristic findings are: microphthalmia, microtia with atresia of the external auditory canal, intrahepatic or extrahepatic biliary atresia and malrotation of the gut. Direct transmission of the marker from one generation to the other was observed in both sexes. In those families, there was considerable variability in the clinical findings between affected family members. These cases show that there is a bias of ascertainment for patients who have the more striking malformations, especially those with ocular coloboma and anal atresia, a combination which appears to be present in only a minority of cases. Many mildly affected patients probably remain undetected. It is proposed that the term Cat Eye syndrome should be applied only to cases with trisomy or tetrasomy of not more than 22pter to q11 and without additional duplication or deletion of another autosomal segment.

Number of patients under 40 years of age given radioiodine therapy between I952 and I962

Williams syndrome (WS) is associated with a submicroscopic deletion of the elastin gene (ELN) at 7q11.23. The deletion encompasses closely linked DNA markers. We have investigated 44 patients referred for possible WS using fluorescence in situ hybridization (FISH) analysis with a P1 clone containing an insert from the ELN, as well as performing genotype analysis of patients and parents with four DNA polymorphisms. Twenty-four patients were found to have deletions, 19 of whom were found clinically to have typical WS. The facial features were especially characteristic. None of the patients without detectable deletions was reported to have typical WS features, although one had supravalvular aortic stenosis, hypercalcemia, and mental retardation. No evidence was found in this material for variability of the size of the deletion. Our study supports the usefulness of analysis of ELN deletion in WS patients, both for confirmation of diagnosis and for genetic counselling.

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