Rapid De tec tion of Intron 22 In ver sions of the Fac tor VIII

dis or der af fect ing ap prox i mately 1 in 10,000 male. The dis ease is caused by a de fi ciency of co ag u la tion fac tor VIII (FVIII) re sult ing from mu ta tions in the FVIII gene. Nu cle o tide sub sti tu tions/in ser tions of var i ous sizes have been iden ti fied through out the FVIII gene. This ge netic di ver sity ac counts for the ob served het er o ge ne ity in clin i cal se ver ity of he mo philia A. A va ri ety of mu ta tions in FVIII gene have been iden ti fied. How ever, most of the gene mu ta tions are unique to one fam ily. No FVIII gene mu ta tions were known to be com mon to a large num ber of pa tients. Car rier de tec tion and pre na tal di ag no sis were thus dif fi cult and of ten re lied on costly in di rect link age anal y sis. Re cently, a mu ta tion caused by a large genomic in ver sion at intron 22 of the FVIII gene was iden ti fied in about 45% of se vere he mo phil i acs. This intron con tains a sec ond gene, FVIII-related gene A (F8A or int22h), tran scribed in the op po site di rec tion to FVIII gene. There are 2 more cop ies of F8A, lo cated ~500 kb up stream of the FVIII gene, and both are tran scribed in the same di rec tion as FVIII gene. This al lows an intrachromosomal ho mol o gous re com bi na tion to oc cur, caus ing an in ver sion of this re gion and sep a rat ing the first 22 exons from exons 23-26 (Fig. 1). This mu ta tion seems com mon to all the races. We ap ply a re verse-transcription poly mer ase chain re ac tion (RT-PCR) method to de tect this im por tant mu ta tion of FVIII gene and to de ter mine the fre quency of this ge netic change in he mo phil i acs in Tai wan.