Inherited biochemical defects affecting the kidney.

The identification of a disease entity as one that is the result of a heritable defect offers the physician an opportunity to intervene in a variety of ways. As emphasized, knowledge of the heritable pattern of a particular disease allows the physician an opportunity to counsel family members in personal disease risk and the offspring. Such genetic counseling results in a reduction of affected cases for many inherited diseases. There is every expectation that similar approaches would be effective for inherited renal diseases. The heritable diseases are a favored group for investigative purposes since these diseases result from a single gene defect no matter how plieotropic the effects of that defect. Thus the investigator is capable of constant probing with tools available for identifying that one event or component that lies at the basis of the disease. The emphasis of this chapter is on those inherited renal diseases for which we have reached a high level of understanding of this single defect. In many of these diseases a single enzyme is identified as deficient and is the presumed genetic defect. In others (cystinuria, RTA, and cystinosis) the precise biochemical answers appear close at hand. Thus a variety of therapeutic approaches to overcome either the gene defect or ill effects of the gene defect emerge for diseases involving the kidney and are listed in Table 7. For some of these diseases the new diagnostic technique of prenatal diagnosis can be used (Table 8). This genetic option provides couples at risk for bearing affected offspring with reduced risk. For a number of other diseases that are not identified by amniocentesis, this risk can be effectively lowered to acceptable levels by use of artificial insemination. Thus the inherited diseases of the kidney are amenable to medical intervention at a variety of levels. Such intervention can predictably lead to a lowering of both the incidence and consequences of these gene defects.