Sixty-seven adolescents participated in this protocol, including 42 with sex chromosome abnormalities and 25 controls. Results from a battery of neuropsychological tests indicated karyotype specific patterns of neuropsychological impairment: (1) 47,XXY boys had unimpaired intelligence but reduced abilities in verbal fluency and reading; (2) 47,XXX girls experienced reduced general intelligence accompanied by impaired scores on individual tests of attention, concept formation, spatial thinking, verbal fluency, and academic skills, while retention of memorized information was a relative strength; (3) among the 45,X girls average intelligence level was also reduced along with scores on tests of attention, concept formation, verbal fluency, spatial thinking, and academic skills, and an atypical pattern of hand dominance was identified; (4) test scores in the group of mosaic females did not differ from those of controls. Test scores and patterns of personal adaptation were quite variable in all groups; while eight nonmosaic propositi required intensive special education assistance in their public schooling, eight others have attended college.

Supernumerary X chromosome material in men is associated with a reduction in left temporal lobe gray matter, a finding that is consistent with the verbal and language deficits associated with KS. Also, relative preservation of gray matter in the left temporal region is associated with exposure to exogenous androgen during development. A history of testosterone supplementation also appears to be associated with increased verbal fluency scores in KS patients.

Children with sex chromosome abnormalities (SCA) are known to be at risk for developmental delays. These risks were identified 2 decades ago by seven international research groups who prospectively followed children ascertained after birth. Subsequently, some of these investigators suggested the course of prenatally identified children with SCA may be different from children in earlier studies. The first such evidence was published by Robinson et al. [1992: Am J Med Genet 44:365-368], who compared 20 prenatally diagnosed children to the original postnatally diagnosed cohort. The following report presents an update and expansion of that research and includes 51 children and adolescents prenatally diagnosed with SCA, now 7-18 years of age. Results confirm that this cohort of prenatally diagnosed children has a milder developmental course than children ascertained postnatally. The study provides new information to health professionals counseling families faced with prenatal diagnosis of SCA.

Sex chromosome abnormalities (SCAs) are the most frequently occurring chromosomal abnormalities encountered at both prenatal diagnosis and at birth. Approximately 1/400 newborns has an SCA, and incidence at prenatal diagnosis is even greater, 1/250 to 1/300. Physicians and health providers from various specialties are encountering diagnoses of SCAs with increased frequency as more individuals are becoming identified, both prenatally and postnatally. Because these conditions generally have relatively few serious physical implications and because they are extremely variable, genetic counseling is often more complex and challenging than that occurring with an autosomal abnormality. It is imperative that health professionals have the knowledge of content and methodology to provide appropriate counseling to such individuals and their families. During the period from 1964 to 1975, seven international groups (including the Denver group) screened a total of 199,898 consecutive births and identified 307 individuals with SCA. The Denver group has followed more than 40 such individuals from birth to adulthood. In addition, the Denver group has experience in counseling over 1,000 families with a prenatal diagnosis of SCA. Based on these studies and contacts, guidelines for the counseling of individuals and families with SCA are provided. Accurate information must be presented and the variability and imprecise prognosis recognized. Successful counseling strategies include interfamily contact, viewing photographs, and utilizing support groups. Issues of disclosure, follow-up, and anticipatory guidance should be addressed.