Nephrogenic diabetes insipidus : Old deletion, new effect. A case report of a family from Greece

Congenital, X-linked, Nephrogenic Diabetes Insipidus (NDI) is a rare disorder in which the kidney is insensitive to the antidiuretic hormone, vasopressin. The gene responsible for this type of NDI, the V2 vasopressin receptor, has been cloned and mapped to Xq28. We report the case of a boy, 2.5 month old, who presented with nephrogenic diabetes insipidus (NDI). The mother and the 7 year old sister of the boy also had the NDI phenotype but did not seek medical attention until the presentation of the boy to our department. The mutational analysis of the patient showed the R337stop mutation, also founded to the mother's genotype analysis. The allele separation in mother revealed the second X chromosomal allele with a 12- bp in-frame deletion. The same in-frame deletion was also found in his sister's genotype. This deletion of four amino acids (Arg-247 to Gly-250) has been previously described but was suggested not to be linked with the NDI phenotype. However, in our case, the only possible cause of NDI phenotype in the boy's sister was the 12-bp in-frame deletion.

Gitelman syndrome: first report of genetically established diagnosis in Greece

Gitelman syndrome is an inherited renal tubular disorder characterized by hypokalemic metabolic alkalosis. It is distinguished from other hypokalemic tubulopathies, such as Bartter syndrome, by the presence of both hypomagnesemia and hypocalciuria. We report a case of Gitelman syndrome in a 10-year-old girl who presented for examination of persistent unexplained hypokalemia. She had no severe clinical symptoms but she had typical laboratory findings including hypokalemia, hypomagnesemia and normocalcemic hypocalciuria. Molecular analysis revealed a mutation in the exon 21 of the SLC12A3 gene which encodes the thiazide-sensitive sodium-chloride co-transporter expressed in the distal convoluted tubule (a guanine to adenosine substitution at nucleotide 2538). She was treated with oral potassium and magnesium supplements. This is the first report of genetically established diagnosis in Greece. Gitelman syndrome should be considered as a cause of persistent hypokalemia and genetic analysis might be a useful tool to confirm the diagnosis.

Nager syndrome (preaxial acrofacial dysostosis): a case report

The Nager syndrome is a rare condition associated with craniofacial malformations such as micrognathia, zygomatic hypoplasia, cleft palate, and preaxial limb deformities. This report features a case of the Nager syndrome occurring in a 4-year-old boy showing microdontia, thumb duplication and radioulnar synostosis, and ventricular septum defect, characteristics not usually encountered in the published cases.