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Salt-Losing 21-Hydroxylase Deficiency Caused by Double Homozygosity for Two "Mild" Mutations
Jacob Ilany1, Jiayan Liu2, Christoph Welsch3
1Institute of Endocrinology, Sheba Medical Center, Tel-Hashomer, Israel.
Context:
Congenital adrenal hyperplasia due to 21-hydroxylase deficiency presents with different severities that correlate with the genotype. The salt-losing phenotype requires 2 alleles with "severe" mutations.
Case Description:
We present a case of salt-losing 21-hydroxylase deficiency that was found to be homozygous for 2 "mild" pathogenic variants: V281L and S301Y. Both in silico and heterologous expression functional analysis demonstrated that co-occurrence of these 2 mutations in cis severely impairs the function of the 21-hydroxylase enzyme.
Conclusions:
This case has important implications for genetic counseling. Regarding this combination of 2 "mild" variants as having mild phenotypic effects could lead to inappropriate counseling of heterozygote carriers.
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