A case report of a presumptive +i(18p) associated with serum IgA deficiency.

The case of a 4-month-old male infant with retarded psychomotor development and multiple anomalies is presented. Cytogenetic studies on peripheral blood and skin cultures revealed a normal male complement with a supernumerary small metacentric chromosome. According to its size and its banding patterns, the metacentric chromosome was postulated to be an isochromosome for the short arm of number 18. A deficiency of serum IgA was observed in this patient.