Hypogammaglobulinaemia in a patient with ring chromosome 21

An 8 year old boy with ring chromosome 21 who wassusceptible to sinorespiratory infections due to hypogammaglobulinaemia is reported. He presented with the characteristic features of monosomy21 syndrome, such as psychomotor retardation, hypertonia, largesaccular ears, prominent nasal bridge, micrognathia, thrombocytopenia, and patent ductus arteriosus. His serum IgG concentration was less than1.5 g/l at 3 years and 6 months of age after repeated hospitalisationswith pneumonia, otitis media, and convulsions. Regular replacement ofintravenous gammaglobulin effectively reduced such infectious episodes.A predisposition to infection in patients with ring chromosome 21 maybe explained by hypogammaglobulinaemia and merit treatment with gammaglobulin.