Hypogammaglobulinemia in a Child with Clericuzio-Type Poikiloderma with Neutropenia

Poikiloderma with neutropenia (PN) is a rare autosomal recessive hereditary disease caused by biallelic mutations of the USB1 gene. It is characterized by poikiloderma, chronic noncyclic neutropenia, and recurrent sinopulmonary infections with bronchiectasis. Here we report a case with homozygous c.531delA mutation in USB1 gene. An 15-month-old boy was admitted to our clinic with skin hyperpigmentation, growth retardation, and recurrent lower respiratory tract infections. The medical history revealed that he was hospitalized 6 times due to pneumonia since the age of 3 months. His physical examination showed facial dysmorphism with triangular face, depressed nasal bridge, and frontal bossing. He also had poikiloderma in the whole body. Skin biopsy was performed and showed only hyperkeratosis. His weight and height were below the 3 percentile. He is the first child of his consangenius parents. In the laboratuary findings; he has mild neutropenia (1,100/mm³), hypogammaglobulinemia (serum IgG: 351 mg/dL, IgA: 17 mg/dL, IgM: 20 mg/dL) and, peripheral lymphocyte subset analysis was normal. Neutropenia was also observed in previous examinations (980-560-840/mm³). Immunoglobulin replacement therapy and antibiotic prophylaxis were started. Exome sequence analysis showed the presence of known homozygous variant (c.351delA) in USB1 gene. Poikiloderma with neutropenia mainly affects the myeloid lineage. Unlike other patients in the literature, we observed hypogammaglobulinemia in addition to neutropenia in our patient. This case illustrated that it is important to monitor serum immunoglobulin levels in symptomatic patients with recurrent infections.