Genetic liver disease in adults. Early recognition of the three most common causes.

The most common clinically important genetic diseases leading to liver dysfunction in adults are Wilson's disease, HHC, and alpha 1AT deficiency. Advances in molecular biology have led to the identification and characterization of the genetic defects in these conditions. Consequently, genetic testing for disease-causing mutations is now available for most of these disorders. However, it is important to understand the strengths and limitations of such testing. Genetic testing is probably most helpful in HHC because of the high frequency of the homozygous C282Y mutation among patients of northern European descent and the relatively high penetrance of the mutation with regard to clinical expression. Genetic testing is much less helpful in the other genetic liver diseases because of the high number of possible mutations and variable clinical expression. However, noninvasive phenotype-based screening tests and specific treatments are available for most genetic liver diseases. Appropriate use of screening tests in routine clinical practice can assist in early identification of genetic liver diseases and prevent development of end-organ damage.