ESPE Yearbook of Paediatric Endocrinology

Annals of pediatric endocrinology & metabolism, 29(3), 156–160. 2024. https://doi.org/10.6065/apem.2448028.014

Brief Summary: This mini-review outlines the application of long-read next-generation sequencing (long-read NGS) in the molecular diagnosis of pediatric endocrine disorders. It highlights various uses of platforms such as Oxford Nanopore Technologies and Pacific Biosciences—including detection of structural variants, repeat expansions, epigenetic changes, and haplotype phasing.

While short-read NGS and array-based CGH have revolutionized genetic diagnostics, they often miss complex structural variants, repeat expansions, and epigenetic abnormalities. Kuroki et al. demonstrate how long-read NGS helps overcome these limitations. Its extended read lengths enable detection of pathogenic variants that remain undetected by conventional methods. Examples include retrotransposon-related variants in GNAS and NR5A1, as well as chromothripsis-related rearrangements (e.g., massive genomic rearrangements caused by a single catastrophic event) seen in endocrine disorders.

A notable application is the CYP21A2 region, associated with 21-hydroxylase deficiency, which is resistant to standard sequencing due to segmental duplications. Long-read NGS also facilitates methylation analysis without bisulfite treatment, useful for diagnosing imprinting disorders like Prader-Willi and Angelman syndromes. Moreover, its haplotype phasing capacity allows for precise determination of compound heterozygosity and mosaic variant origin.

Several limitations persist, including higher base-calling error rates compared to short-read NGS, costs, technical complexity, and limited accessibility. However, recent advancements, such as adaptive sampling and rapid sequencing workflows, have significantly improved the accuracy, speed, and practicality of long-read NGS. As these innovations continue to evolve, long-read NGS is poised to become an indispensable diagnostic tool for rare or unexplained pediatric endocrine conditions and a cornerstone of future precision medicine.