Disorder
Gitelman variant of Bartter’s syndrome
Clinical Characteristics
General description (for patients):
This condition causes periodic mild paralysis, fatigue, muscle cramps and rarely convulsions from severe loss of potassium and electrolyte imbalance. Blood levels of magnesium are often low as well. Low potassium may lead to irregularity of the heart beat. Kidney damage can result and blood volume sometimes is low contributing to the weakness. Unsteadiness, dizziness, and blurred vision can also occur. Severe illness or vigorous exercise may worsen all of these symptoms.
Medical description (for healthcare providers):
This is a specific form of the classic salt-losing Bartter syndrome in which a defect in the thiazide-sensitive Na-Cl cotransporter leads to severe hypokalemia and hypomagnesemia. Volume depletion is not as severe as in true Bartter syndrome, but patients can suffer from weakness, fatigue, dizziness, ataxia, and blurred vision. More often, periodic paralysis, tetany, and muscle cramping lead to complaints but do so in older individuals, especially following serious illness or strenuous exercise. Signs in infants include dehydration, weakness, and failure to thrive but the relative mildness of this condition often does not lead to the diagnosis until the 2nd or 3rd decades. Hypokalemia may cause ventricular arrhythmias, tachycardias, and renal damage. Hypocalcinuria is common.
Genetics:
Gitelman syndrome is an autosomal recessive disorder resulting from a mutation in the SLC12A3 or thiazide-sensitive Na-Cl cotransporter gene located on chromosome 16 (16q13). Amish/Mennonite patients have been found in Northern Indiana and in Pennsylvania. It has been reported that the antenatal variety of Bartter syndrome, type 2, (#241200) has been found in the Amish of southeastern Pennsylvania, but with a 7 exon deletion in the chloride channel gene CLCNKB (see *602023). Another variety of Gitleman syndrome with a 1924C>A substitution has also been reported in the same population.
Management:
Vigorous treatment with potassium replacement is sufficient to alleviate most symptoms.
Electrolyte monitoring.
Prognosis:
Excellent.
Specialists and specialty centers:
Nephrologist, endocrinologist, internist.
References:
Gitelman, H.J., Graham, J.B., and Welt, L.G.: A new familial disorder characterized by hypokalemia and hypomagnesemia. Trans. Assoc. Am. Phys. 79: 221-235, 1966. PubMed ID: 5929460
Simon, D.B., Nelson-Williams, C., Bia, M.J., Ellison, D., Karet, F.E., Molina, A.M., Vaara, I., Iwata, F., Cushner, H.M., Koolen, M., Gainza, F.J., Gitelman, H.J., and Lifton, R.P.: Gitelman’s variant of Bartter’s syndrome, inherited hypokalaemic alkalosis, is caused by mutations in the thiazide-sensitive Na-Cl cotransporter. Nature Genet. 12: 24-30, 1996. PubMed ID: 8528245
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