A Spanish founder mutation in the chloride channel gene, CLCNKB, as a cause of atypical Bartter syndrome in adult age.
BACKGROUND
Mutations in the chloride channel gene, CLCNKB, usually cause classic Bartter syndrome (cBS) or a mixed Bartter-Gitelman phenotype in the first years of life.


METHODS
We report an adult woman with atypical BS caused by a homozygous missense mutation, A204T, in the CLCNKB gene, which has previously been described as the apparently unique cause of cBS in Spain.


RESULTS
The evaluation of this patient revealed an overlap of phenotypic features ranging from severe biochemical and systemic disturbances typical of cBS to scarce symptoms and diagnosis in the adult age typical of Gitelman syndrome. The tubular disease caused a dramatic effect on mental, growth and puberal development leading to low IQ, final short stature and abnormal ovarian function. Furthermore, low serum PTH concentrations with concomitant nephrocalcinosis and normocalcaemia were observed. Both ovarian function and serum PTH levels were normalized after treatment with cyclooxygenase inhibitors.


CONCLUSIONS
The present report confirms a weak genotype-phenotype correlation in patients with CLCNKB mutations and supports the founder effect of the A204T mutation in Spain. In our country, the genetic diagnosis of adult patients with hereditary hypokalaemic tubulopathies should include a screening of A204T mutation in the CLCNKB gene.
Gorgojo
Juan José
JJ
Unit of Endocrinology and Nutrition, Fundación Hospital Alcorcón, Madrid, Spain. jjgorgojo@fhalcorcon.es
Donnay
Sergio
S
Jeck
Nikola
N
Konrad
Martin
M
D000328:Adult; D001477:Bartter Syndrome / Q000097:blood / Q000145:classification / Q000235:genetics*; D018118:Chloride Channels / Q000235:genetics*; D005260:Female; D018703:Founder Effect; D006801:Humans; D017354:Point Mutation; D013030:Spain / Q000453:epidemiology
D018118:Chloride Channels