A Mutation in the IL-2 Receptor .GAMMA. Chain Gene Associated with X-linked Severe Combined Immunodeficiency Accompanying Opisthotonus

Abstract

Severe combined immunodeficiency (SCID) is an inherited disease with profoundly defective T cells, B cells, and NK cells. X-linked severe combined immunodeficiency (X-SCID) is its most common form. In this report, we describe a 4-month old male with X-SCID who also showed opisthotonic posturing. Opisthotonus represents abnormal motor posturing and is defined as the posturing, in which the neck and back are arched posteriorly. The patient was referred to our hospital with liver dysfunction, respiratory distress, anal abscess, poor feeding and wasting; the patient appeared to suffer from severe and persistent infections. In fact, circulating T cells were not detectable, despite that the number of B cells was maintained in the normal ranges. Diagnosis of X-SCID was established by DNA analysis of the interleukin (IL)-2 receptor gamma chain gene; namely, we detected the novel mutation within exon 2 (221 C-->A), which leads to the substitution of tyrosine codon for stop codon (Y69stop). Computed tomography of the brain revealed mild atrophy, but no hemorrhage and no malformation. There were no pathological findings in the cerebrospinal fluid. Thus, the cause of opisthotonic posturing remains unknown. The patient died due to severe infection at the age of 7 months. It remains to be investigated to clarify the relationship between the mutation and clinical manifestations. In conclusion, we have identified the novel mutation in the IL-2 receptor gamma chain gene, which is associated with X-SCID. Furthermore, this is the first report that describes the patient with X-SCID accompanying opisthotonus.