Advances in Genetic Prediction and Diagnosis
Recombinant DNA technology has revolutionized the study of genetic influences in disease. There now exists a low resolution linkage map of DNA markers covering the whole human genome and the loci involved in most common monogenic disorders have been mapped. This permits first trimester prenatal diagnosis and carrier detection within most affected families using the generalized strategy of gene tracking. It has also allowed the cloning of the dystrophin gene (the site of the Duchenne muscular dystrophy mutation) and other genes by “reverse genetics”. Direct detection of the mutation causing a monogenic disease is becoming easier; A technique that has assisted in this is the million fold or more amplification of a known target DNA sequence by the polymerase chain reaction. DNA amplification facilitates the elucidation of protein sequence variations in populations that represent susceptibility genes to common multifactorial disease. Much of the heritability of insulin-dependent diabetes mellitus (IDDM) has now been shown to reside in the identity of amino acid 57 of the HLA class II molecule the DQB-chain. Aspartic acid in this position appears to protect against IDDM. It is hoped that elucidation of genetic influences in disorders of complex etiology will help clarify the non-genetic influences and allow people to maximize their chance of good health.
KeywordsSickle Cell Anemia Prenatal Diagnosis Duchenne Muscular Dystrophy Prenatal Test Gene Tracking
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