Management

Management
•    Acute management: aggressive sodium and fluid repletion; correct metabolic acidosis.
•    Long-term: sodium and bicarbonate supplementation as needed; monitor growth and development.
•    Surveillance: monitor for potential intestinal inflammation; consider multidisciplinary care (gastroenterology, nephrology, genetics).
•    Reproductive counseling: carriers may be asymptomatic; consider CFTR testing if male infertility with vas deferens abnormalities is present (possible digenic/oligogenic interactions).

Genetic Counselling
SLC9A3-related congenital secretory sodium diarrhea (CSD) has an autosomal inheritance pattern.

•    For infants with unexplained secretory diarrhea with high fecal sodium, consider SLC9A3gene sequencing, especially in consanguineous families and when features like polyhydramnios or intestinal dilation antenatally are present; in male infertility (CBAVD) and CF lung disease, SLC9A3may be part of the genetic work‐up or modifier analyses. General concerns about sampling fetal material and diagnosing genetic conditions late in pregnancy would apply.
•    Genetic testing: sequencing of SLC9A3 (e.g., exome or targeted gene panel) looking for homozygous/compound heterozygous variants; functional confirmation may aid interpretation.
•    Heterozygous de novo variants might present with milder or different phenotypes — interpretation requires caution (variant of uncertain significance vs pathogenic).
•    Genetic counselling: for the classical syndrome, autosomal recessive inheritance gives 25% recurrence risk for siblings when both parents are carriers.
•    Awareness of possible inflammatory bowel disease and male infertility variant phenotypes is important for broadening the diagnostic scope.

If the pathogenic variant occurred de novo (new) in the patient (i.e. it was not detected in the parents), the recurrence risk in subsequent pregnancies of the proband’s parents is generally low (<1%). The genetic ‘carrier’ may pass the variant on to their children, but is unlikely to cause symptoms. Inheriting an abnormal gene from both parents (25% recurrence risk) will cause the disease and can affect males and females equally. Prenatal diagnosis is possible, if requested by the parents.