A novel mutation in KCNJ1 in a Bartter syndrome case diagnosed as pseudohypoaldosteronism.
Bartter syndrome (BS) is a genetic disorder with hypokalemic metabolic alkalosis and is classified into five types. One of these, type II BS (OMIM 241200), is classified as neonatal Bartter syndrome, which is caused by mutations in the KCNJ1 gene. Transient hyperkalemia and hyponatremia are usually noted in the early postnatal period, but as type II BS is a relatively rare disease, its exact clinical course and genetic background have not yet been thoroughly characterized. This report concerns a male type II BS patient with a novel mutation in the KCNJ1 gene. The unique clinical findings of this case are that hyperkalemia (8.9 mEq/l), hyponatremia, and metabolic acidosis detected in the early postnatal period led to a diagnosis of pseudohypoaldosteronism (PHA). As an adolescent, however, the patient currently shows normal potassium levels and normal renal function, although with hypercalciuria and nephrocalcinosis, without having received any treatment. In such cases, KCNJ1 mutations should be suspected. In our case, genetic analysis of the KCNJ1 gene identified a novel homozygous 1-bp deletion mutation (c.607 del. C in exon 5).
Nozu
Kandai
K
Department of Pediatrics, Kobe University Graduate School of Medicine, and Shinko Hospital, Kobe 650-0017, Kusunokicho 7-5-1, Chuo, Kobe, Hyogo, Japan. nozu@med.kobe-u.ac.jp
Fu
Xue Jun
XJ
Kaito
Hiroshi
H
Kanda
Kyoko
K
Yokoyama
Naoki
N
Przybyslaw Krol
Rafal
R
Nakajima
Toshihiro
T
Kajiyama
Mizutaka
M
Iijima
Kazumoto
K
Matsuo
Masafumi
M
D000293:Adolescent; D001477:Bartter Syndrome / Q000097:blood / Q000145:classification / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D005500:Follow-Up Studies; D006720:Homozygote; D006801:Humans; D053565:Hypercalciuria; D006947:Hyperkalemia; D007010:Hyponatremia; D007902:Length of Stay; D008297:Male; D009154:Mutation; D010375:Pedigree; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics*; D011546:Pseudohypoaldosteronism / Q000150:complications / Q000175:diagnosis*
C086989:KCNJ1 protein, human; D024661:Potassium Channels, Inwardly Rectifying