Ataxia-telangiectasia (AT) is a multisystemic neurodegenerative disorder characterized by ataxia, telangiectasia, and immunodeficiency. Although elevated serum levels of IgM with decreased IgA and IgG levels have been reported in about 10% of the AT cases during their course of the disease, it is a rare finding at the onset and may cause to delay of diagnosis or misdiagnosis as hyper-IgM syndrome.
A 6-years-old boy referred our clinic due to hypogammaglobulinemia. He had been followed up with an autoimmune thrombocytopenia and hemolytic anemia at the age of 1.5 years. He was born to consanguineous parets and had history of recurrent sinopulmonary infections. Physical examination revealed growth retardation and mild gait disturbance.Serum IgG and IgA levels were low and IgM level was 519 mg/dl. CD19 lymphopenia was detected. AFP level was high and diagnosis of ataxia-telangiectasia was confirmed by detecting ATM homozygous mutation. The patient was treated with IVIG replacement, prophylactic antibiotic and antifungal.
During the follow-up, neurological findings and telangiectasias progressively increased. The patient is still followed up without infection or hemolysis by IVIG replacement and prophylactic antibiotics.
Since cerebellar ataxia and ocular telangiectasia may not be present in infancy, the diagnosis of AT may be delayed during this period. Also the patients presenting with elevated IgM serum levels may be misdiagnosed as HIGM syndrome. As in this case, the diagnosis of AT should be kept in mind in patients with primary immune deficiency with abnormal neurological findings and autoimmunity.