F. Clarke Fraser

The inheritance of the aarskog facial-digital-genital syndrome

Prominent physical features of the Aarskog syndrome are short stature, telecanthus, ptosis, short broad nose, long philtrum, thin upper vermilion border and pouty lower lip, low-set jug-handle ears, short broad hands with clawlike positioning of the fingers, broad feet with bulbous toes, ventral scrotal folds, cryptorchidism, and hernias. Four families with 20 affected males are reported. Pedigree analysis is compatible with X-linked recessive inheritance with occasional partial expression in heterozygote females. The fact that seven sons, all unaffected, have been born to affected males argues against the alternative hypothesis of autosomal sex-influenced inheritance.

47,X,i(Xq),Y karyotype in Klinefelter's syndrome

SummaryThis is a case report of 47,X,i(Xq),Y in a 24-year-old infertile male with Klinefelters syndrome. C staining indicated that this isochromosome X had a single small centromere. BUdR incorporation revealed the isochromosome X to be late replicating.

767 GENETICS OF OSTEOGENESIS IMPERFECTA TYPE II

Osteogenesis Imperfecta Type II (OI, lethal perinatal) has been presumed to be inherited as an autosomal recessive trait. In an attempt to test this hypothesis questionnaires were sent to all University Departments of Medical Genetics in Canada, requesting information about their ascertained cases of OI Type II. Twenty-three kindreds were ascertained with a total of 23 sibs of which 4 (17.4%) were affected. By the “singles” method of Davie (Ann. Hum. Gen. 42, 507, 1979) the estimated segregation frequency was 0.17±0.024. The sex ratios of affected and normal individuals did not differ significantly from expectation. There was no recognized parental consanguinity. The segregation ratio is significantly lower than 0.25 (P<0.01), suggesting the presence of either selective prenatal mortality or of genetic heterogeneity. These findings support the contention of Young and Harper (Lancet I, 432, 1980) that the empiric recurrence risk for 01 Type II is less than 25%.

QUANTITATIVE EVALUATION OF ABNORMAL FEATURES IN SELECTED SYNDROMES

Statements that certain syndromes are characterized by abnormal dimensions of facial features or body proportions are often subjective and lack statistical backing. We have compared the cephalic index, inter outer and inner canthal distances, interpupillary distance, ear height and length, philtrum length, angle at elbow, hand size, hand/finger ratio, internipple/chest circumference ratio and upper/lower segment ratio in normal children and patients with DeLange, Noonan, and XO Turner syndromes. Many comparisons demonstrate statistically significant differences. For instance, in DeLange syndrome, the digits are short, relative to the palm. In Noonan syndrome the ears are low set but not appreciably so in Turner syndrome. The ratio of sitting height to height is increased in Turner syndrome as is the internipple to chest circumference.