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Case Reports
. 2024 Nov;12(11):e70029.
doi: 10.1002/mgg3.70029.

Long-Read Sequencing Identifying the Genetic Complexity of Congenital Adrenal Hyperplasia in the Pedigree

Ximin Chen  1 , Jing Zhao  2 , Danhua Li  3 , Na Xi  1 , Danying Yi  1 , Mengjia Yan  1 , Yan Yin  1 , Xueyan Wang  1
Affiliations
Case Reports

Long-Read Sequencing Identifying the Genetic Complexity of Congenital Adrenal Hyperplasia in the Pedigree

Ximin Chen et al. Mol Genet Genomic Med. 2024 Nov.

Abstract

Background: High sequence homology between CYP21A2 and CYP21A1P poses challenges to genetic diagnosis of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD). Traditional genetic testing is unable to provide an accurate diagnosis due to the genetic complexity of CAH.

Methods: Deletions, duplications, and recombination breakpoints were precisely identified by long-read sequencing (LRS).

Results: This study presented a pregnant woman, a 21-OHD carrier detected by MLPA, and her husband, a normal subject also detected by MLPA. The fetus was suspected of having 21-OHD based on clinical presentations such as enlarged adrenal glands, atypical external genitalia and karyotyping of 46, XX. LRS further identified the fetus as having the most severe salt-wasting (SW) form of 21-OHD with a compound heterozygote genotype. One allele was TNXA/TNXB CH-2, while the other allele was CYP21A1P/CYP21A2 CH-8. LRS precisely determined the genotypes of the fetus's father and grandmother with duplications, which misdiagnosed by MLPA. The multidisciplinary team recommended immediate glucocorticoid and mineralocorticoid treatment for the child after birth to prevent life-threatening adrenal crisis.

Conclusions: LRS provides precise diagnosis for family members with CYP21A2 deletion or duplication, improving disease management and preventing potential adrenal crises. When used in pre-pregnancy genetic testing, LRS can indicate high genetic risk and guide the appropriate therapy during pregnancy and immediately after birth.

Keywords: compound heterozygote; congenital adrenal hyperplasia; long‐read sequencing; prenatal diagnosis.

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Conflict of interest statement

D.L are employees of Berry Genomics Corporation. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Color Doppler ultrasound Images at 23 weeks plus 5 days of pregnancy. (A) Transverse ultrasound sections of the abdomen showing enlarged left adrenal gland. (B) Long‐axis view of the left kidney. (C) Transverse ultrasound sections of the abdomen revealing normal right adrenal gland. LAG: Left adrenal gland. RAG: Right adrenal gland. SP: spine. LK: left kidney. ST: stomach.
FIGURE 2
FIGURE 2
Color Doppler ultrasound Images at 27 weeks plus 5 days of pregnancy. Long‐axis view of the left idney (A) and right kidney (B) showing enlarged adrenal gland. (C) The clitoral enlargement and thickened labia majora visualized by the ultrasound imaging of external genitalia. LAG: left adrenal gland. RAG: right adrenal gland. LK:left kidney. RK: right kidney. ST: stomach. LM: labia majora.
FIGURE 3
FIGURE 3
The genotypes of family members identified by LRS and depicted by IGV plots and schematic diagram. CYP21A2: CYP21A2 without pathogenic variants. CYP21A1P/A2 CH‐8: CYP21A1P/CYP21A2 CH‐8; TNXA/B CH‐2: TNXA/TNXB CH‐2; a duplicated CYP21A2: The fusion gene of functional gene TNXB and pseudogene TNXA. WT: Wild type. Blue box: The break interval of CYP21A1P/CYP21A2 CH‐8; Red box: The break interval of TNXA/TNXB CH‐2; Black box: The break interval of a duplicated CYP21A2. Dashed line: Chimeras resulted from meiotic unequal crossover.
FIGURE 4
FIGURE 4
Pedigree chart of the investigated family.
See this image and copyright information in PMC

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References

    1. Auer, M. K. , Nordenström A., Lajic S., and Reisch N.. 2023. “Congenital Adrenal Hyperplasia.” Lancet 401, no. 10372: 227–244. - PubMed
    1. Cantürk, C. , Baade U., Salazar R., Storm N., Pörtner R., and Höppner W.. 2011. “Sequence Analysis of CYP21A1P in a German Population to Aid in the Molecular Biological Diagnosis of Congenital Adrenal Hyperplasia.” Clinical Chemistry 57, no. 3: 511–517. - PubMed
    1. Carrozza, C. , Foca L., De Paolis E., and Concolino P.. 2021. “Genes and Pseudogenes: Complexity of the RCCX Locus and Disease.” Frontiers in Endocrinology (Lausanne) 12: 709758. - PMC - PubMed
    1. Chen, W. , Kim M. S., Shanbhag S., et al. 2009. “The Phenotypic Spectrum of Contiguous Deletion of CYP21A2 and Tenascin XB: Quadricuspid Aortic Valve and Other Midline Defects.” American Journal of Medical Genetics. Part A 149a, no. 12: 2803–2808. - PMC - PubMed
    1. Chen, W. , Xu Z., Sullivan A., et al. 2012. “Junction Site Analysis of Chimeric CYP21A1P/CYP21A2 Genes in 21‐Hydroxylase Deficiency.” Clinical Chemistry 58, no. 2: 421–430. - PMC - PubMed

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