Comparison of Phenotypic Assessment and Mutation Detection in the Diagnosis of Carrier State in Hemophilia: Identification of 10 Novel Mutations.

The carrier state in 54 females (A38, B16) at risk from 35 moderate and severe hemophilia families (A25, B10) in Thailand, was determined. They were classified as obligate (A17, B8) and possible (A21, B8) carriers by history taking. The phenotypic assessment was performed in two subsequent blood samples taken one week apart when they were not pregnant or on birth control pills. Then, molecular genetics among hemophiliac patients were performed. Inversion of intron 22 among 25 hemophilia A patients was initially performed. Then, the mutations were intensively detected by using conformation sensitive gel electrophoresis (CSGE). Coding region, intron/exon boun-daries, and 5′ and 3′ regions of the factor VIII and IX genes were amplified in 33 separate reactions in hemophilia A patients without inversion of intron 22 (n=10) and 9 separate reactions in hemophilia B patients (n=10). Samples displaying abnormal CSGE profiles were numbered according to Wood et al and Yoshitake et al. The results revealed that mutation were found at 88% (22/25, 15 inversion of intron 22 and 7 mutations) in hemophilia A and 90% (9/10) in hemophilia B patients. Ten were novel mutations as shown in Table 1. Also, the carrier state assessed by the phenotypic study and mutation detections are shown in Table 2. As a result, the phenotypic assessment alone showed a limitation in the diagnosis of carrier state especially hemophilia B carrier while the mutation detections provide an absolute diagnosis over phenotypic assessment.

Table 1. The identified ten novel mutations among Thai hemophilia A and B patients.

Table 2. Carrier state assessed by phenotypic study and mutation detections among females at risk.