Targeted long-read sequencing identifies missing pathogenic variant in unsolved 11β-hydroxylase deficiency

Area of Science:

• Genetics
• Endocrinology
• Molecular Biology

Background:

• 11β-hydroxylase deficiency (11β-OHD) is a common cause of congenital adrenal hyperplasia (CAH).
• Genetic testing for 11β-OHD is challenging due to CYP11B1/CYP11B2 gene similarities and complex structural variants.
• This study investigates the genetic basis of 11β-OHD in a Chinese family.

Purpose of the Study:

• To identify the underlying genetic causes of 11β-OHD in two siblings from a Chinese family.
• To evaluate the efficacy of advanced sequencing techniques for diagnosing 11β-OHD.

Main Methods:

• Clinical data and peripheral blood samples were collected.
• Sex steroid concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
• Long-range PCR-based next-generation sequencing (NGS) and target long-read sequencing (T-LRS) were employed to detect pathogenic variants in the CYP11B1 gene.

Main Results:

• Both siblings presented with early-onset hypertension, elevated ACTH, progesterone, and testosterone, alongside decreased cortisol and potassium.
• NGS identified a heterozygous missense variant (c.281C>T, p.P94L) in CYP11B1.
• T-LRS detected a novel deletion-insertion variant (c.954+78_980delinsACAG) in trans with the missense variant, confirming the genetic diagnosis.

Conclusions:

• The combined approach of long-range PCR-based NGS and T-LRS provides a reliable and accurate method for 11β-OHD genetic diagnosis.
• This integrated strategy is effective for identifying complex CYP11B1 variants and for carrier sequencing in families affected by 11β-OHD.