Recurrent V75M mutation within the Wiskott-Aldrich syndrome protein: description of a homozygous female patient

[The gene mutation analysis of a Wiskott-Aldrich syndrome family with normal mean platelet volume]

目的

调查1个血小板平均体积（MPV）正常的Wiskott-Aldrich综合征（WAS）患者家系资料，分析先证者及其母亲WASP基因突变情况，探讨WAS的临床特征。

方法

以1个四代共22人WAS家系为研究对象，调查该家系成员病史，采集先证者及母亲外周血标本并提取DNA，采用一代基因测序进行WASP基因全部外显子突变分析。

结果

先证者及其哥哥MPV均正常。先证者WAS临床评分5分，抗PM-Scl抗体阳性，抗PCNA抗体阳性，抗核糖体P蛋白抗体阳性，抗链球菌溶血素明显增高。先证者合并有自身免疫性疾病、贫血、肾功能异常、真菌感染及巩膜炎。先证者WASP基因2号外显子173号碱基C>T纯合突变，导致第58号氨基酸由脯氨酸异变为亮氨酸。先证者母亲为WASP突变携带者。先证者CBL、CREBBP、DNM2及ADAMTS13基因突变频率明显高于正常人群。

结论

该例WAS患者WASP基因173C>T突变，无湿疹，MPV正常，伴有自身免疫性疾病，为国内首次报道；其母亲为WASP突变携带者。WAS基因突变检测有助于早期识别和确诊WAS。

A novel primary human immunodeficiency due to deficiency in the WASP-interacting protein WIP

A homozygous mutation that gave rise to a stop codon in the WIPF1 gene resulted in WASP protein destabilization and in symptoms resembling those of Wiskott-Aldrich syndrome

A female offspring of consanguineous parents, showed features of Wiskott-Aldrich syndrome (WAS), including recurrent infections, eczema, thrombocytopenia, defective T cell proliferation and chemotaxis, and impaired natural killer cell function. Cells from this patient had undetectable WAS protein (WASP), but normal WAS sequence and messenger RNA levels. WASP interacting protein (WIP), which stabilizes WASP, was also undetectable. A homozygous c.1301C>G stop codon mutation was found in the WIPF1 gene, which encodes WIP. Introduction of WIP into the patient’s T cells restored WASP expression. These findings indicate that WIP deficiency should be suspected in patients with features of WAS in whom WAS sequence and mRNA levels are normal.

X-linked thrombocytopenia (XLT) due to WAS mutations: clinical characteristics, long-term outcome, and treatment options

A large proportion of patients with mutations in the Wiskott-Aldrich syndrome (WAS) protein gene exhibit the milder phenotype termed X-linked thrombocytopenia (XLT). Whereas stem cell transplantation at an early age is the treatment of choice for patients with WAS, therapeutic options for patients with XLT are controversial. In a retrospective multicenter study we defined the clinical phenotype of XLT and determined the probability of severe disease-related complications in patients older than 2 years with documented WAS gene mutations and mild-to-moderate eczema or mild, infrequent infections. Enrolled were 173 patients (median age, 11.5 years) from 12 countries spanning 2830 patient-years. Serious bleeding episodes occurred in 13.9%, life-threatening infections in 6.9%, autoimmunity in 12.1%, and malignancy in 5.2% of patients. Overall and event-free survival probabilities were not significantly influenced by the type of mutation or intravenous immunoglobulin or antibiotic prophylaxis. Splenectomy resulted in increased risk of severe infections. This analysis of the clinical outcome and molecular basis of patients with XLT shows excellent long-term survival but also a high probability of severe disease-related complications. These observations will allow better decision making when considering treatment options for individual patients with XLT.

Primary Immunodeficiencies

Primary immunodeficiencies (PIDs), once considered to be very rare, are now increasingly recognized because of growing knowledge in the immunological field and the availability of more sophisticated diagnostic techniques and therapeutic modalities [161]. However in a database of >120,000 inpatients of a general hospital for conditions suggestive of ID 59 patients were tested, and an undiagnosed PID was found in 17 (29%) of the subjects tested [107]. The publication of the first case of agammaglobulinemia by Bruton in 1952 [60] demonstrated that the PID diagnosis is first done in the laboratory. However, PIDs require specialized immunological centers for diagnosis and management [33]. A large body of epidemiological evidence supports the hypothesis of the existence of a close etiopathogenetic relation between PID and atopy [73]. In particular, an elevated frequency of asthma, food allergy (FA), atopic dermatitis and enteric pathologies can be found in various PIDs. In addition we will discuss another subject that is certainly of interest: the pseudo-immunodepressed child with recurrent respiratory infections (RRIs), an event that often requires medical intervention and that very often leads to the suspicion that it involves antibody deficiencies [149].

Detection of 28 novel mutations in the Wiskott–Aldrich syndrome and X-linked thrombocytopenia based on multiplex PCR

The Wiskott-Aldrich syndrome (WAS) is an X-linked disorder including microthrombocytopenia, eczema and immunodeficiency. A mild form is known as the X-linked thrombocytopenia (XLT). We screened 150 individuals or families based on a multiplex PCR method. We found 28 novel mutations (7 missense, 1 nonsense, 1 nonstop change, 5 splice site mutations and 14 deletions or insertions). The method relied on the co-synthesis of 5 amplicons and direct sequencing, optimizing the novel protocol proposed by Jones et al. [L.N. Jones, M.I. Lutskiy, J. Cooley, et al. A novel protocol to identify mutations in patients with Wiskott-Aldrich syndrome, Blood Cells Mol. Dis. 28 (2002) 392-398]. It was thus possible to identify faster and at a lower cost the mutations in newly diagnosed patients. The mutation distribution, according to the type, was in keeping with the distribution reported previously. No clear-cut genotype-phenotype correlation was observed.