Preliminary Study On Genotype-Phenotrpe Correlation Of Chinese Wiskott-Aldrich Syndrome Patients

Objective: to study genotype-phenotype correlation preliminarily in 24 Chinese patients with Wiskott-Aldrich syndrome (WAS).Methods: clinical data of 24 Chinese WAS patients admitted to The Children's Hospital, Chongqing Medical University from April 2009 to November 2010 were collected, the patients' phenotypes were scored according to international scoring standards. Flow cytometry technology was used to analyze WAS protein (WASP) expression in peripheral blood mononuclear cells (PBMCs). WASP gene was directly sequenced, then the genotype-phenotype correlation was analyzed.Results: 24 patients were all male, 2 of them were X-linked thrombocytopen ia (XLT) with scores 2, the others were classic WAS with scores 3-5. One patient's WASP normally expressed, one's expression reduced, and the others' WASP expressions were negative. We found 7 missense, 3 nonsense, 7 deletion, and 7 splice site mutations. 21 unique mutations were detected, including 3 novel mutations which were 180 C>T(A49V), 342-343del CA(S103fsX121),IVS7+2 T>C. There were 6 hot spot mutations were reported which were 291 G>A (R86H), 291G>T (R86L), 1035del G (G334fsX444), 665 C>T (R211X), IVS6+5 G>A, and IVS8+1 G>A. Two patients with missense mutations manifested as XLT, whereas the others with missense mutations were classic WAS. All nonsense, deletion and splice site mutations patients were classic WAS, some of whose phenotype were severe.Conclusion: Clinical phenotypes of most of the missense mutations appeared to be more severe than what have been reported by others, the reason for this was currently unknown and probably associated with late diagnosis and irregular therapy. Mutations in downstream of WASP gene, nonsense, deletion and splice site mutations probably led to negative expression of WASP, unstable or trancated WASP produced. However, environmental influence which might worsen patients' phenotypes could not be underestimated. Objective: to study the possible genotype-phenotype correlation of a Wiskott-Aldrich syndrome patient with spontaneous in vivo reverse mutation.Methods: clinical data of this patient was collected, whose phenotype was scored. Flow cytometry was used to analyse WAS protein (WASP) expression in peripheral blood mononuclear cells (PBMCs). WASP gene was directly sequenced, cDNA was subcloned and sequenced to know the relative proportions of primary and reverse mutation genotypes in the RT-PCR products, then the genotype-phenotype correlation was analysed.Results: the patient was a 12-year-old male, phenotype scored 2 at the time admitted to Chongqing Children's hospital, he stayed alive without life-threatening diseases since 10 years of age. WASP was partially expressed, the primary mutation was 155 C>T. While 85% (17/20) of cDNA subclones were the primary mutation genotype, the rest 15% (3/20) clones shew nucleotide C at 155 site indicating normal genotype.Conclusion :the reverse mutation might modify disease severity of Wiskott-Aldrich syndrome to some extent. The mechanism for in vivo spontaneous reverse mutation and its long-term impact on immune function and outcome was currently not clear.