Selective IgM deficiency and 22q11.2 deletion syndrome

Abstract

The 22q11.2 deletion syndrome is a common chromosomal disorder with highly variable phenotypic expression and immunologic defects. Humoral immunity is mostly unaffected, but selective IgA deficiency occurs in up to 13% of patients. Selective IgM deficiency associated with 22q11.2 deletion has been reported in 1 patient. To describe another 2 patients with 22q11.2 deletion syndrome and IgM deficiency. Patient 1 was a 6-year-old boy with recurrent otitis media, sinopulmonary infections, wheezing, and speech delay. His serum IgM level was 18 mg/dL, and his IgA and IgG levels were normal. Antibody titers to protein and carbohydrate antigens were protective. Workup for velopharyngeal insufficiency resulted in the diagnosis of 22q11.2 deletion syndrome 3 years later. Patient 2 was a 14-year-old girl diagnosed as having 22q11.2 deletion at 9 years of age after presenting with neonatal seizures, atrial and ventricular septal defects, recurrent otitis media, mental retardation, and asthma. Her serum IgM level was 11 mg/dL, with normal IgG and IgA levels. Antibody titers to protein and carbohydrate antigens were protective. Patient 3 was a previously described 15-year-old girl with persistently draining ears, 22q11.2 deletion, and an IgM level less than 6 mg/dL. Her clinical and laboratory features are summarized. Results of further testing on the patients, including lymphocyte enumeration, were normal. The literature is reviewed regarding decreased IgM levels in 22q11.2 deletion syndrome. Fluorescence in situ hybridization analysis for chromosome 22q11.2 deletion should be considered in patients with selective IgM deficiency, especially if concurrent chronic otitis media, developmental delay, velopharyngeal insufficiency, or dysmorphic features are present.