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Akhkiamova M, Polyakov A, Marakhonov A, Voronin S, Saifullina E, Vafina Z, Michalchuk K, Braslavskaya S, Chukhrova A, Ryadninskaya N, Kutsev S, Shchagina O. Rare Variants of the SMN1 Gene Detected during Neonatal Screening. Genes (Basel) 2024; 15:956. [PMID: 39062735 PMCID: PMC11275604 DOI: 10.3390/genes15070956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 07/12/2024] [Accepted: 07/13/2024] [Indexed: 07/28/2024] Open
Abstract
During the expanded neonatal screening program conducted in 2023, we analyzed samples obtained from 1,227,130 out of 1,256,187 newborns in the Russian Federation in order to detect 5q spinal muscular atrophy (5q SMA). Within the 253-sample risk group formed based on the results of the first screening stage, 5 samples showed a discrepancy between the examination results obtained via various screening methods and quantitative MLPA (used as reference). The discrepancy between the results was caused by the presence of either a c.835-18C>T intronic variant or a c.842G>C p.(Arg281Thr) missense variant in the SMN1 gene, both of which are located in the region complementary to the sequences of annealing probes for ligation and real-time PCR. Three newborns had the c.835-18C>T variant in a compound heterozygous state with a deletion of exons 7-8 of the SMN1 gene, one newborn with two copies of the SMN1 gene had the same variant in a heterozygous state, and one newborn had both variants-c.835-18C>T and c.842G>C p.(Arg281Thr)-in a compound heterozygous state. Additional examination was carried out for these variants, involving segregation analysis in families, carriage analysis in population cohorts, and RNA analysis. Based on the obtained results, according to the ACMG criteria, the c.835-18C>T intronic variant should be classified as likely benign, and the c.842G>C p.(Arg281Thr) missense substitution as a variant of uncertain clinical significance. All five probands are under dynamic monitoring. No 5q SMA symptoms were detected in these newborns neonatally or during a 1-year follow-up period.
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Affiliation(s)
- Maria Akhkiamova
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Aleksander Polyakov
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Andrey Marakhonov
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Sergey Voronin
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Elena Saifullina
- Bashkir State Medical University, Lenin Str., 3, 450008 Ufa, Russia;
| | - Zulfiia Vafina
- Republic of Tatarstan Ministry of Healthcare Autonomous Public Healthcare, Institution Republic Clinical Hospital, Orenburgskiy Tract Str., 138, 420064 Kazan, Russia;
| | - Kristina Michalchuk
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Svetlana Braslavskaya
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Alena Chukhrova
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Nina Ryadninskaya
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Sergey Kutsev
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
| | - Olga Shchagina
- Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia; (A.P.); (A.M.); (S.V.); (K.M.); (S.B.); (A.C.); (N.R.); (S.K.); (O.S.)
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