{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,21]],"date-time":"2026-08-21T04:26:52Z","timestamp":1787286412906,"version":"build-2736575974"},"reference-count":43,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T00:00:00Z","timestamp":1787097600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Research Foundation of Capital Institute of Pediatrics","award":["JCYJ-2023-03"],"award-info":[{"award-number":["JCYJ-2023-03"]}]},{"award":["JCYJ-2023-03"],"award-info":[{"award-number":["JCYJ-2023-03"]}],"id":[{"id":"https:\/\/ror.org\/00zw6et16","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Natural Science Foundation of Beijing Municipality","award":["L212035"],"award-info":[{"award-number":["L212035"]}]},{"name":"Natural Science Foundation of Beijing Municipality","award":["7212005"],"award-info":[{"award-number":["7212005"]}]},{"name":"Beijing Finance Bureau","award":["11000024T000002831273"],"award-info":[{"award-number":["11000024T000002831273"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Background: Spinal muscular atrophy (SMA) is mainly caused by biallelic SMN1 inactivation. While most patients carry homozygous deletions, 3\u20135% are compound heterozygotes, making molecular diagnosis challenging. Methods: A tiered diagnostic strategy was applied to 17 pediatric patients, combining copy number analyses (MLPA and targeted long-read sequencing, tLRS), sequence variant detection (RT-PCR cloning and sequencing, allele-specific long-range PCR with nested PCR, and tLRS), and structural variant analysis (ultra-long-read sequencing, Ultra-LRS). Results: Copy numbers were concordant between MLPA and tLRS. MLPA-suggested gene conversions were confirmed by tLRS, while discordant total copy numbers were resolved as large deletions by Ultra-LRS. RT-PCR cloning, and sequencing identified SMN1 variants in 11\/12 cases and confirmed aberrant splicing in three cases, but failed for large deletions. AS-LR-PCR with nested PCR characterized the variants in 13\/15 but failed in gene conversion cases. tLRS achieved definitive diagnosis in all cases, and Ultra-LRS precisely delineated breakpoint junctions of two large deletions. Conclusions: A hierarchical complementary strategy integrating copy number, sequence, and structural analyses is essential for the accurate diagnosis of compound heterozygous SMA.<\/jats:p>","DOI":"10.3390\/genes17080971","type":"journal-article","created":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T09:30:53Z","timestamp":1787131853000},"page":"971","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Molecular Genetic Diagnosis of Spinal Muscular Atrophy: Clinical Utility, Challenges, and Lessons Learned from Illustrative Cases in a Single Center"],"prefix":"10.3390","volume":"17","author":[{"given":"Jinli","family":"Bai","sequence":"first","affiliation":[{"name":"Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing 100020, China"},{"name":"Department of Medical Genetics, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qinglin","family":"Jiang","sequence":"additional","affiliation":[{"name":"Department of Medical Genetics, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hui","family":"Jiao","sequence":"additional","affiliation":[{"name":"Department of Neurology, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuwei","family":"Jin","sequence":"additional","affiliation":[{"name":"Department of Medical Genetics, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hong","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Medical Genetics, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiushan","family":"Ge","sequence":"additional","affiliation":[{"name":"Department of Neurology, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ying","family":"Gao","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoyin","family":"Peng","sequence":"additional","affiliation":[{"name":"Department of Neurology, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fang","family":"Song","sequence":"additional","affiliation":[{"name":"Department of Medical Genetics, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2959-3754","authenticated-orcid":false,"given":"Yujin","family":"Qu","sequence":"additional","affiliation":[{"name":"Department of Medical Genetics, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mei","family":"Diao","sequence":"additional","affiliation":[{"name":"Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing 100020, China"},{"name":"Department of Pediatric Surgery, Capital Center for Children\u2019s Health, Capital Medical University, Capital Institute of Pediatrics, Beijing 100020, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2120","DOI":"10.1016\/S0140-6736(08)60921-6","article-title":"Spinal muscular atrophy","volume":"371","author":"Lunn","year":"2008","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1586\/14737159.4.1.15","article-title":"Spinal muscular atrophy: Molecular genetics and diagnostics","volume":"4","author":"Ogino","year":"2004","journal-title":"Expert. 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