Familial isolated congenital asplenia

Familial isolated congenital asplenia (FICA), also known as isolated congenital asplenia or hereditary splenic agenesis, is an extremely rare condition characterized by the complete absence of the spleen from birth without any other associated developmental abnormalities. Unlike asplenia that occurs as part of heterotaxy syndromes (where the arrangement of internal organs is disrupted), familial isolated congenital asplenia occurs as an isolated finding, meaning the heart and other organs develop normally. The condition primarily affects the immune system, as the spleen plays a critical role in filtering blood and mounting immune responses against encapsulated bacteria. Patients with FICA are at severely increased risk of life-threatening, overwhelming bacterial infections (known as overwhelming post-splenectomy infection or OPSI-like sepsis), particularly from encapsulated organisms such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. These fulminant infections can occur at any age but are especially dangerous in infancy and early childhood, and they carry a high mortality rate if not promptly recognized and treated. The condition may go undiagnosed until a severe septic episode occurs, as the absence of the spleen may not cause obvious symptoms otherwise. Characteristic blood smear findings include Howell-Jolly bodies (nuclear remnants in red blood cells that are normally removed by the spleen). Management of familial isolated congenital asplenia focuses on infection prevention and includes lifelong prophylactic antibiotics (typically penicillin, especially in childhood), comprehensive vaccination against encapsulated bacteria (pneumococcal, meningococcal, and Haemophilus influenzae type b vaccines), and prompt empiric antibiotic treatment for any febrile illness. Patient and family education about the risks of infection is essential. Mutations in the RPSA gene (encoding ribosomal protein SA) have been identified as a cause of this condition in multiple families. Genetic counseling is recommended for affected families.

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