Genetic counseling for sex chromosome abnormalities

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.