A Unique Genotype of Pseudohypoaldosteronism Type 1b in a Highly Consanguineous Population.

CONTEXT: Pseudohypoaldosteronism (PHA) is a condition in which serum aldosterone level is normal or elevated but its action is deficient. OBJECTIVE: This study describes the molecular genetics of PHA 1b in the highly consanguineous population of 2 Arabian Gulf countries, Saudi Arabia and Oman. METHODS: This study enrolled 22 patients from 13 unrelated families (2 families with 5 patients from Oman and 11 families with 17 patients from Saudi Arabia). All of these patients had presented within the first 10 days of life with nausea and vomiting, hyponatremia, hyperkalemia, and hypotension. We isolated DNA from peripheral blood and PCR-sequenced all exons and exon-intron boundaries of SCNN1A and, if negative, SCNN1B and SCNN1G using the Dideoxy Chain termination method. RESULTS: We found a total of 8 mutations in 13 families as follows: 6 mutations in SCNN1A, 1 in SCNN1B, and 1 in SCNN1G. All of these mutations were novel except one. SCNN1A mutations were: c.1496A>G, p.Q499R (novel) in 1 patient; c.1453C>T, p.Q485X (novel) in 1 patient; c.1322_1322delA, p.N441Tfs*41 (novel) in 2 patients of 1 family; c.876 + 2 delGAGT (novel) in 3 patients of 1 family; c.203_204 delTC, p.I68Tfs*76 (a known mutation) in 8 patients of 5 families; and whole SCNN1A gene deletion (novel) in 2 patients of 2 families. In addition, a nonsense SCNN1B mutation c.1694C>A, p.S565X (novel) was found in 3 siblings from 1 Omani family, and an SCNN1G deletion mutation c.527_528 delCA, p.T176Rfs*9 (novel) in 2 siblings from another Omani family. CONCLUSION: We characterized a unique genotype of PHA 1b with several novel gene structure-disrupting mutations in SCNN1A, SCNN1B, and SCNN1G in a highly consanguineous population.

Variable phenotype in five patients with Wolcott-Rallison syndrome due to the same EIF2AK3 (c.1259delA) mutation.

Wolcott-Rallison syndrome (WRS) is a rare condition characterized by permanent neonatal diabetes (PND), skeletal dysplasia, and recurrent hepatitis. Other features, including central hypothyroidism, have been reported. We compared the phenotype of five patients from two families with WRS caused by the same EIF2AK3 mutation who have been followed up since diagnosis. Direct sequencing of the EIF2AK3 gene identified a homozygous frameshift mutation (c.1259delA) in all patients that has been reported only in these families. All patients presented with PND and four experienced recurrent hepatitis. A 3.5-year-old girl has isolated PND, whereas her younger sister has typical WRS features. Two children developed skeletal abnormalities and two had transient central hypothyroidism. Other reported features of WRS were not detected. The EIF2AK3 c.1259delA mutation results in a variable phenotype, ranging from isolated PND to typical WRS. Thyroid dysfunction in WRS is a transient phenomenon reflecting euthyroid sickness.