Seeds J W, Cefalo R C, Miller D T, Blatt P M
Obstet Gynecol. 1983 Sep;62(3 Suppl):23s-25s.
Hemophilia B (factor IX deficiency) is an X-linked recessive clotting disorder similar to hemophilia A. In both diseases, phenotypic expression of the disorder may occur in significant numbers of heterozygous carriers. This is presumably due to random inactivation of one of the two X chromosomes of the female carrier as described by the Lyon hypothesis. Described herein is the obstetric care of a severely affected heterozygous carrier of hemophilia B. Predelivery automated plasma exchange was used to raise factor IX levels successfully. Commercial factor concentrates were avoided. The Lyon hypothesis is discussed in detail, and recommendations are made for the care of the clotting factor-deficient gravid woman.
乙型血友病（因子IX缺乏症）是一种与甲型血友病相似的X连锁隐性凝血障碍。在这两种疾病中，相当数量的杂合子携带者可能会出现该疾病的表型表达。这可能是由于如莱昂假说所述，女性携带者两条X染色体中的一条随机失活所致。本文描述了一位严重受影响的乙型血友病杂合子携带者的产科护理情况。产前采用自动血浆置换成功提高了因子IX水平。避免使用商业因子浓缩物。详细讨论了莱昂假说，并对凝血因子缺乏的孕妇护理提出了建议。
