Moesin deficiency was initially described in 7 male participants aged 4 to 69 years and is characterized by lymphopenia of the 3 lineages and moderate neutropenia. Genetically, 6 out of 7 participants had the same missense mutation in the moesin gene located on the X chromosome. The 7th patient has a mutation leading to the premature introduction of a STOP codon into the protein.Clinically the 7 participants with X-linked moesin-associated immunodeficiency all presented with recurrent bacterial infections of the respiratory, gastrointestinal or urinary tracts, and some had severe varicella.Therapeutically, in the absence of a molecular diagnosis and due to his SCID-like phenotype, one patient was treated with geno-identical hematopoietic stem cell transplantation . The remaining are untreated or treated with immunoglobulin substitution and/or prophylactic antibiotics.

Since this study, the moesin gene has been integrated into DNA chips used for the molecular diagnosis of immune deficiencies in several countries. Physicians in Canada, the United States, Japan, South Africa and Europe have contacted us with a total of 16 known participants to date. Because of their very low severe, uncontrolled CMV infection and the absence of treatment recommendations, two 2 American participants were treated with allogeneic transplantation with severe post-transplant complications (1), and one of the participants died as a result of the transplant. Management of XMAID participants therefore varies widely from country to country, depending on age at diagnosis and clinical picture. It ranges from no treatment treatment (associated with recurrent infections and skin manifestations), IgIv substitution and/or antibiotic prophylaxis antibiotic prophylaxis, with low toxicity and apparent efficacy, and allogeneic transplantation, with all the risks risks involved (graft-related toxicity, graft versus host, disease, rejection, risk of infection). The Investigators therefore feel it is important to review the diagnosis, clinical presentation and management of X-MAID participants. The study the investigator propose will enable to understand the presentation of X-MAID participants, establish guidelines and provide the best treatment for each patient according to his or her clinical picture

Since this study, the moesin gene has been integrated into DNA chips used for the molecular diagnosis of immune deficiencies in several countries. Physicians in Canada, the United States, Japan, South Africa and Europe have contacted us with a total of 16 known participants to date. Because of their very low severe, uncontrolled CMV infection and the absence of treatment recommendations, two 2 American participants were treated with allogeneic transplantation with severe post-transplant complications (1), and one of the participants died as a result of the transplant. Management of XMAID participants therefore varies widely from country to country, depending on age at diagnosis and clinical picture. It ranges from no treatment treatment (associated with recurrent infections and skin manifestations), IgIv substitution and/or antibiotic prophylaxis antibiotic prophylaxis, with low toxicity and apparent efficacy, and allogeneic transplantation, with all the risks risks involved (graft-related toxicity, graft versus host, disease, rejection, risk of infection). The investigators therefore feel it is important to review the diagnosis, clinical presentation and management of X-MAID participants. The study the investigators propose will enable to understand the presentation of X-MAID participants, establish guidelines and provide the best treatment for each participant according to his or her clinical picture

Inclusion Criteria:

• Male patient with a mutation in the MOESIN gene (MSN)
• No objection to the collection of personal health data

Exclusion Criteria:

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The participants are male patients (children or adults) with a mutation in the MOESIN gene (MSN) associated with an immune deficiency, regularly monitored in hospital centers because only male patients are affected by this disease, which is linked to a mutation of a gene on the X chromosome. This will enable us to determine whether symptoms and responses to treatment differ according to mutation.

The disease can be diagnosed in the first year of life. Patients are therefore either children or adults.

Given the small number of participants and the purpose of the study, the group may include deceased patients (at least 1 of the 16 participants). The sample size is 16 patients already identified, and possibly other patients who may be identified once the existence of the the existence of the international registry. Final enrolment will correspond to all X-MAID patients diagnosed worldwide who agree to take part in the study.