X-linked hyper IgM syndrome: A report of the first case in Thailand with aconfirmed mutation of CD40 ligand gene

X-linked hyper IgM (XHIM) syndrome is a rare congenital immunodeficiency di sease caused by failure of a cell to isotype switch from IgM to other class es of immunoglobulins in response to infections. Recently, a molecular clon ing of the gene responsible for the syndrome, the CD40L gene has been accom plished and the gene was successfully mapped to the long arm of X chromosom e at the position Xq26. We, herein, report the first case of molecular prov en XHIM in a Thai boy with a classic presentation and with a confirmed muta tion of the CD40L gene. Case Report: A.S. was a 1 year 7 month old boy refe rred from Buriram provincial Hospital for a work up and treatment for his r ecurrent infections consisted of chronic respiratory tract infections with otitis media (since 6 months of age), chronic diarrhea (since 9 months of a ge) and malnutrition (marasmus) secondary to his longstanding illnesses. He was a product of a consanguineous marriage but without history of similar illness observed in his pedigree. Abnormal laboratory works up included IgG of 300 mg/dl, IgA 10 mg/dl, IgM 1,635 mg/dl, positive stool examinations f or Cryptosporidium, chronic colitis on radiographic gastrointestinal follow through study, a positive acid fast bacillus (AFB) stain of gastric aspira te and multiple positive bacterial cultures from various body sources. His anti-HIV serology was negative. His hospital course was significant for sev eral bouts of infections of gastrointestinal, respiratory, and genitourinar y systems. His treatment consisted of multiple courses of antibiotics, anti tuberculous drugs and IVIG administrations. His hospital course was complic ated with feeding problem from an esophageal stricture requiring several es ophageal dilatations. The analysis of CD40L gene revealed a point mutation of exon 5 (A619T) of the CD40L gene resulting in a stop codon confirming th at indeed he had XHIM. He died with Pseudomonas septicemia during the waiti ng period for a bone marrow transplantation from a cord-blood stem cell.