The genetics of neurologic syndromes.

Diagnosis and counseling represent the two primary functions of the clinical geneticist. To establish a diagnosis, the geneticist must be familiar with the entire gamut of genetic and nongenetic disorders. Even when the diagnosis is made by laboratory tests or physical examination, the pervasiveness of genetic/etiologic heterogeneity demands that the geneticist be skilled in the extraction of a thorough family history and in the subtleties of pedigree interpretation. Multiple specialty referrals may be solicited. Counseling is an involved process that includes a thorough discussion of the nature, etiology, and prognosis of the disorder; its burden; its recurrence risk; and the alternatives at the family's disposal for dealing with that risk. Calculation of the recurrence risk itself may require special mathematical techniques. For parents to assimilate this extensive information, they must be receptive. If they are grieving heavily, denying the existence of the problem, or busy tending to the medical or financial needs of their child, counseling is seriously compromised. For these reasons, geneticists may assume the responsibility of coordinator of services to facilitate the difficult experience of bearing a child with a serious developmental disorder. Only then can be adequately perform the functions for which he has been trained.