Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành y đề tài: To the Editor: We have diagnosed a patient from Quebec . | Letter To the Editor We have diagnosed a patient from Quebec with hyperimmunoglobulin M hyper-IgM syndrome resulting from a defect in activation-induced cytidine deaminase AID . The patient s mutation proved to be identical to that of all other French Canadians with AID defects. This case illustrates the clinical nature of AID deficiency and review of the relevant literature sheds light on what is being called the French-Canadian AID mutation. The patient was referred to our clinic at the age of 16 years. He had had chronic cervical lymphadenopathy since the age of 2 years and also had recurrent sinopulmonary infections consistent with bacterial pathogens. He had not experienced any severe viral or opportunistic infection. One paternal grandmother and one maternal grandmother were sisters. Examination revealed normal height and weight cervical lymphadenopathy a left middle-ear effusion and bilateral lower-lobe expiratory crackles. A chest radiograph was suggestive of bronchiectasis. A complete blood count complement levels and T- and B-cell enumerations were normal. Levels of all antibodies were low except that of IgM which was significantly elevated at 7.93 g L normal 0.56-3.52 . The result of a CD154 binding assay was normal. Sequencing of the AID gene demonstrated a homozygous C-to-T mutation at position 334 resulting in cysteine replacing arginine at position 112 of the protein. In every French-Canadian patient with AID deficiency there have been 15 such patients if our patient is included a homozygous R112C mutation has been found.1 These findings are suggestive of a founder effect. A founder effect can occur when a small group of people from one population separate and form a new population. An allele that had a rare frequency in the parent population may then have a higher frequency in the new population simply because one or more of the founders happened to carry the rare allele. If the new population remains isolated as it expands as has been the case in .
