Screening for carrier state of Haemophilia B using indirect genomic detection

: The authors report the first data having applied the indirect genomic diagnosis in carrier screening in Hungary. 22 patients with haemophilia B and female family members of 14 out of them were examined by PCR based restriction fragment length polymorphism analysis. The combined use of 3 intra- and 1 extragenic polymorphisms have been examined at the same population. DNA fragments, containing the single nucleotide change polymorphic site (Xmnl, Hhal, Taql), or the 50 bp insertion/deletion element (Dde) were amplified. The products were digested by the appropriate restriction digestion enzyme and were detected on agarose gel following ethidium-bromide staining. 20 siblings were interested in the determination of their carrier-state. 15 (75%) of them could get definite diagnosis. The carrier-state was established in 7 cases, excluded in 8 subjects. For the remaining 5 participants studied, the absence of the parental DNA sample caused uncertainty, while in 2 cases (10%) none of the analyzed RFLP was informative. The heterozygosity rate, the gene and haplotype frequency were also recorded and compared with the international data. The indirect methods have proved to be sufficient and well suitable for routine carrier testing. The results provide the basis of the subsequent prenatal diagnosis.