Families

Prevalence
The SLC9A3-related disorder—an autosomal-recessive form of congenital secretory sodium diarrhea (CSD)—is very rare (estimated prevalence <1/1,000,000).

Clinical characteristics
Females carrying a child with autosomal-recessive CSD typically present prenatally with polyhydramnios in the third trimester, a pregnancy condition where there is an excess of amniotic fluid causing prominent abdominal distention in utero due to high fetal intestinal fluid output. Following birth, neonatal infants produce a profuse watery diarrhea with high fecal and low serum sodium levels, alkaline fecal pH and more acidic blood pH. Infants become irritable and eventually lethargic, and exhibit moderate to severe dehydration. The infants will not thrive if left untreated. Afflicted individuals may require prolonged sodium and bicarbonate supplementation in early life; growth may normalize if carefully managed.

Other reported features observed in some individuals with defective SLC9A3include the later development of ileal/colonic ulceration and inflammatory‐bowel‐disease (IBD)-like features during childhood and adolescence (variable expressivity) and potentially male infertility (if present in individuals with cystic fibrosis).

Inheritance
Since the SLC9A3gene is located on chromosome 5, SLC9A3-related conditions are known as autosomal recessive conditions. The genetic mechanism is typically requires inheriting an abnormal gene from both parents (25% recurrence risk) to cause the disease and can affect males and females equally.