De la Morena et al. (1995) reported a 6-month-old Hispanic girl of Chinese and Peruvian Indian ancestry who presented at age 3.5 months with interstitial pneumonia and gastroenteritis. Laboratory studies showed agammaglobulinemia, neutropenia, and lack of mature B ... De la Morena et al. (1995) reported a 6-month-old Hispanic girl of Chinese and Peruvian Indian ancestry who presented at age 3.5 months with interstitial pneumonia and gastroenteritis. Laboratory studies showed agammaglobulinemia, neutropenia, and lack of mature B cells in the peripheral blood and bone marrow. Lymph nodes showed lack of B cells, plasma cells, and germinal center formation. T cells and T-cell function were normal. Presence of CD10+ cells but absence of CD19+ cells and a 10-fold decrease of mature V-D-J-C-mu transcripts suggested a blockage at an earlier stage of B-cell development than that observed in the X-linked form of agammaglobulinemia (300755); genetic analysis excluded a defect in the BTK gene (300300). Conley et al. (2012) provided follow-up of the patient reported by de la Morena et al. (1995), who was 19 years old and showed a severe defect in very early B-cell development. As a teenager, she developed erythema nodosum, juvenile idiopathic arthritis, and recurrent Campylobacter bacteremia and inflammatory bowel disease, suggesting disordered cytokine production. The family history was positive for 2 older brothers and 2 maternal uncles who died of acute infections between 9 and 18 months of age.
In a patient with agammaglobulinemia-7, Conley et al. (2012) identified a homozygous truncating variant in the PIK3R1 (W298X; 171833.0001). The mutation, which was identified by exome sequencing, segregated with the disorder and was not found in 1,000 in-house ... In a patient with agammaglobulinemia-7, Conley et al. (2012) identified a homozygous truncating variant in the PIK3R1 (W298X; 171833.0001). The mutation, which was identified by exome sequencing, segregated with the disorder and was not found in 1,000 in-house control alleles. Screening of the PIK3R1 gene in 55 additional patients with defects in B-cell development did not identify any other mutations.