[Mutation analysis of WASP gene and prenatal diagnosis of Wiskott-Aldrich syndrome].

OBJECTIVE

Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency characterized by microthrombocytopenia, eczema, recurrent infections, and an increased incidence of autoimmunity and malignancies. The patients always have a severe clinical phenotype that can result in death if not diagnosed and treated early in life. The treatment of choice with the best outcome is hematopoietic stem cell transplantation, preferably from a matched related donor. But uncertain treatment effect and high treatment cost limit its clinical application. It is the best strategy that avoiding birth of a fetus with defect through prenatal diagnosis at present. This study aimed to analyze the mutation of WASP gene in 4 Chinese families with WAS and to provide prenatal diagnosis for the high-risk fetus.

METHOD

The probands of the four WAS families were all males, one of whom was deceased but had a family history and clinical datas integrated. All the patients were detected with blood routine tests, immunological tests and bone marrow examination. PCR and bilateral direct sequencing of PCR product was carried out in the regions of exon and exon-intron boundaries of WASP gene for 3 probands, 4 mothers and 100 unrelated healthy individuals as control. Prenatal diagnosis was provided for the two fetuses at the first trimester by mutation analysis.

RESULT

Four WASP gene mutations were detected: c.91A > G (p.E31K), c.665C > T (p.R211X), c.397G > A (p.E133K), c.952-953delCC (p. P317fsX18), among which c.952-953delCC (p. P317fsX18) was first reported. Mothers in Family 2, 3 and 4 were carriers of WASP gene mutation, but family 1 was considered as a de-novo mutation. None of the 100 unaffected subjects had the above mutants. Prenatal diagnosis indicated that the fetus in family 2 was male and carried the same mutation as the proband, so the fetus was presumably to be a patient. The parents decided to receive an induced abortion. Following the termination of the pregnancy, the result of gene analysis of the aborted tissues was consistent with prenatal diagnosis. The fetus in family 3 was normal male confirmed by normal test results six months after birth.

CONCLUSION

The 4 mutations of the WASP gene probably were causative to the families of WAS, among which c.952-953delCC was reported for the first time. Prenatal diagnosis by DNA sequencing is the effective method to avoid birth of WAS patient.