Open AccessNucleotide Sequence of the Na + /H + Exchanger‐8 in Patients With Congenital Sodium Diarrhea
Author(s) -
Baum Michel,
Martin Martin G.,
Booth Ian W.,
Holmberg Christer,
Twombley Katherine,
Zhang Qiuyu,
Gattineni Jyothsna,
Moe Orson
Publication year - 2011
Publication title -
journal of pediatric gastroenterology and nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.206
H-Index - 131
eISSN - 1536-4801
pISSN - 0277-2116
DOI - 10.1097/mpg.0b013e318227ad6e
Subject(s) - brush border , sodium–hydrogen antiporter , diarrhea , sodium , medicine , hyponatremia , gene isoform , endocrinology , microbiology and biotechnology , membrane , gene , biochemistry , biology , vesicle , chemistry , organic chemistry
ABSTRACT Sodium absorption by the intestine is mediated by brush border Na + /H + exchangers, which include the NHE3 and NHE8 isoforms. We demonstrated a maturational decrease in NHE8 and increase in NHE3 in mouse intestine mRNA abundance and brush border membrane protein abundance, indicating a developmental switch of isoforms. Congenital sodium diarrhea is a rare autosomal recessive disorder characterized by polyhydramnios, hyponatremia, metabolic acidosis, and diarrhea with a high sodium content. Previous studies using intestinal brush border membrane vesicles from patients with this disorder have demonstrated a decrease in Na + /H + exchanger activity. Because some patients with congenital sodium diarrhea improve with age and knowing the developmental switch from NHE8 to NHE3, NHE8 may be a candidate gene for this disorder. We sequenced NHE8 from 5 patients with this disorder and found no disease‐causing homozygous mutations. Although brush border membrane Na + /H + exchange activity may be decreased, exonic mutations in NHE8 cannot account for this disorder in these subjects.