Isolated congenital asplenia is a rare disease in humans that can cause life-threatening bacterial infections in children due to primary immunodeficiency. The infections can include pneumococal sepsis and meningitis. Isolated congenital asplenia is a rare disease in humans that can cause life-threatening bacterial infections in children due to primary immunodeficiency. The infections can include pneumococal sepsis and meningitis. ICAS is a ribosomopathy, due to autosomal dominant mutation of the RPSA gene on chromosome 3p21. Unlike heterotaxy syndrome, the absent spleen is not associated with other structural developmental defects.