Genetics in pediatrics.

The prevalence of genetic disease in the pediatric population is considerable and probably accounts for at least 50% of childhood deaths and 25% of hospital pediatric admissions. A simple three-generation family history is often very useful, as is background information on ethnicity and consanguinity. A preponderance of affected males in a family should immediately suggest an X-linked recessive disorder which may have widespread implications for female relatives in the family. Chromosomal errors will usually be associated with developmental handicaps and one or more major or minor dysmorphic signs. Disorders involving secondary sexual characteristics are largely genetic in origin. Many disorders which were previously thought to be one entity are now known to be many different entities (genetic heterogeneity).