Wilkins-Haug L
Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Curr Opin Obstet Gynecol. 1993 Apr;5(2):179-85.
Usually, genetic diseases segregate in a stable, predictable fashion throughout a family. For many inherited disorders, a mutation at the DNA level has been characterized, and prenatal diagnosis is available. Recently, however, the dogma of traditional mendelian inheritance has been challenged by the discovery of new patterns of gene segregation and expression. Unstable DNA segments varying in size have been associated with both fragile X syndrome and myotonic dystrophy and can now be diagnosed by direct DNA analysis. Uniparental disomy, the inheritance of both members of a chromosome pair from one parent, has been documented in autosomal and X-linked recessive diseases. Imprinted genes, the expression of which is dependent on the parent of origin, are being increasingly identified, especially in syndromes with abnormalities of growth. In the near future, the number of prenatally diagnosed disorders will expand as tests for unstable DNA, uniparental disomy, and imprinting become widely available.
通常情况下，遗传疾病在一个家族中以稳定、可预测的方式进行分离。对于许多遗传性疾病，DNA水平的突变已得到明确，并且可以进行产前诊断。然而，最近，传统孟德尔遗传的教条受到了新的基因分离和表达模式发现的挑战。大小各异的不稳定DNA片段与脆性X综合征和强直性肌营养不良均有关联，现在可以通过直接DNA分析进行诊断。单亲二体，即一对染色体的两个成员均来自同一亲本，已在常染色体和X连锁隐性疾病中得到证实。印记基因的表达取决于其起源的亲本，目前越来越多地被发现，尤其是在生长异常的综合征中。在不久的将来，随着针对不稳定DNA、单亲二体和印记的检测广泛应用，产前诊断疾病的数量将会增加。
