Table 2.

Molecular Genetic Testing Used in 21-Hydroxylase-Deficient Congenital Adrenal Hyperplasia

Gene 1MethodProportion of Probands with Pathogenic Variants 2 Detectable by Method
CYP21A2 Sequence analysis 3~70%-80% 4
Gene-targeted deletion/duplication analysis 5~20%-30% 6
1.
2.

See Molecular Genetics for information on allelic variants detected in this gene.

3.

Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.

4.

The majority of individuals from heterogeneous populations with 21-OHD CAH are compound heterozygotes [Krone et al 2000, New et al 2013].

5.

Gene-targeted deletion/duplication analysis detects intragenic deletions or duplications. Methods used may include quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and a gene-targeted microarray designed to detect single-exon deletions or duplications.

6.

Approximately 20% of mutated alleles are deleted for a 30-kb gene segment that encompasses the 3' end of the CYP21A1P pseudogene, all of the adjacent C4B complement gene, and the 5' end of CYP21A2 (see Molecular Genetics).

From: 21-Hydroxylase-Deficient Congenital Adrenal Hyperplasia

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