Haemophilia A in a female with a novel INV22 mutation and skewed X-chromosome inactivation / 中华检验医学杂志

ABSTRACT

0bjective To make genetic and prenatal diagnosis of a female with Haemophilia A.Methotis The FⅧC.BT and VWF were detected to make phenotypic diagnosis.LD-PCR was adopted for screening the intron 22 inversion and PCR was adopted for the screening the intron 1 inversion.The coding and boundary sequences of FⅧgene were analyzed by PCR and DNA equencing.Eight combined polymorphie markers(Amelo,F8IVS13,CA22,DXS15,DXS9901,G6PD,DXS1073 and DXS1108)were applied for linkage analysis of the family by multiplex fluorescent PCR.The polymorphism of DXS52 (ST14)was analyzed by PCR and electrophoresis. Assessment of X inactivation was performed using an Hpa II-polymerase chain eaction (PCR)assay for the X-inked human androgen receptor gene(HUMARA). Results The female HA patient showed severe FW deficiency(FⅧC 2.1%)and other phenotypie tests were normal.Her family members showed normal in all tests.The female proposita was found to be a carrier of FW gene intron 22 inversion.But her family members as well as her etus showed negative results.Except this inversion,no other mutation Wag found then.The female inherited two X chromosomes from both her parents' and her fetus inherited the maternally derived X chromosome from the female proposita according to the linkage analysis.Furthermore.X-inactivation paRern of the female was unbalanced and her aternally derived X chromosome Wag inaetived mostly while the majority of her paternal derived one kept active.Conclusions The severe haemophilia A in the proposita resulted from the de novo Ⅷ intron 22 inversion which most probably arose in the paternal germ line.Associated with a skewing pattern of inactivation of the maternally derived X chromosome.Her etus is normal female.