Natural history and clinical manifestations of hyponatremia and hyperchlorhidrosis due to carbonic anhydrase XII deficiency.
BACKGROUND
We identified patients of Bedouin origin with a mutation in carbonic anhydrase XII (CA XII) leading to hyponatremia due to excessive salt loss via sweat.


METHODS
The medical records of patients were reviewed for clinical and laboratory data.


RESULTS
A total of 11 subjects were identified; 7 symptomatic patients presented with hyponatremic dehydration in infancy. Screening of the entire kindred identified 4 asymptomatic individuals with elevated sweat chloride. All symptomatic patients had failure to thrive and moderate-severe hyponatremia (106-124 mmol·l(-1)); 6 had hypochloremia (79-94 mmol·l(-1)). All asymptomatic subjects had normal or near-normal serum sodium and chloride concentrations. Both symptomatic and asymptomatic subjects had normal renal functions and normal cortisol response on low-dose ACTH test. All symptomatic patients were treated by dietary salt, which prevents episodes of hyponatremic dehydration and promotes growth. At follow-up, the chief complaints remained heat intolerance, accumulation of salt precipitates on the face and hyperhidrosis. No evidence for chronic renal, respiratory, gastrointestinal or fertility abnormalities was found.


CONCLUSIONS
Recognizing this newly described entity and differentiating it from cystic fibrosis and pseudohypoaldosteronism are important. Patients with CA XII mutations should be followed even after early childhood, especially in hot temperatures and intense physical activity.
Pediatric Endocrinology Unit, Soroka Medical Center, Faculty of Health Sciences, Beer Sheva, Israel.
Yael
Y
Feinstein
Baruch
B
Yerushalmi
Neta
N
Loewenthal
Soliman
S
Alkrinawi
Ohad S
OS
Birk
Ruti
R
Parvari
Eli
E
Hershkovitz
D000293:Adolescent; D000328:Adult; D002256:Carbonic Anhydrases / Q000172:deficiency*; D002648:Child; D002675:Child, Preschool; D003681:Dehydration / Q000209:etiology / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008661:Metabolism, Inborn Errors / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009154:Mutation; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*; D013542:Sweat
D017673:Sodium Chloride, Dietary; D002256:Carbonic Anhydrases; C477378:carbonic anhydrase XII