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A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia

Cilt: 31 22 Ekim 2026
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A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia

Öz

Opsismodysplasia (OPS; OMIM #258480) is an ultra-rare autosomal recessive skeletal dysplasia caused by biallelic pathogenic variants in INPPL1, which encodes the lipid phosphatase SHIP2. Although synonymous variants are increasingly recognised as pathogenic through aberrant splicing, they remain underappreciated in the molecular diagnosis of rare skeletal disorders. We investigated a female infant presenting with severe short stature and characteristic skeletal abnormalities, using whole-exome sequencing (WES), followed by Sanger sequencing, segregation analysis, splice-site prediction, evolutionary conservation assessment, and mRNA secondary-structure modelling. Clinical and radiological evaluation demonstrated severe platyspondyly, disproportionate micromelia, metaphyseal cupping, complete absence of carpal ossification, and characteristic craniofacial features consistent with OPS. WES identified a novel homozygous synonymous variant, INPPL1 c.1197G>A, p.(Arg399=), which was confirmed by Sanger sequencing, while both parents were heterozygous carriers. In silico analyses predicted a marked weakening of the canonical exon 10 donor splice site, along with activation of two cryptic donor sites, strongly suggesting aberrant splicing. The affected nucleotide was highly conserved (PhyloP = 4.813; PhastCons = 1.0), and RNAfold predicted increased diversity of mutant mRNA ensembles, supporting altered transcript stability. This study reports the first synonymous splice-altering variant in INPPL1, expanding the molecular spectrum of OPS and highlighting the importance of systematic evaluation of synonymous variants in rare skeletal dysplasias. Functional RNA-based studies are warranted to confirm the predicted splicing defect.

Anahtar Kelimeler

Opsismodysplasia, INPPL1, Synonymous variant, Splice-altering variant, Whole-exome sequencing

Etik Beyan

Ethical approval for the study was obtained from the Institutional Review Board of Başakşehir Çam and Sakura City Hospital (Approval No: 309454473; Date: 06 April 2026).

Kaynakça

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  2. Ashish, A., Mishra, S., Singh, R., & Rai, S. (2025). Clinical exome sequencing (carrier screening) identifies the gene INPPL1 in a sporadic case of opsismodysplasia. European Journal of Clinical and Experimental Medicine, 23(1), 277–282. https://doi.org/10.15584/ejcem.2025.1.32
  3. Below, J. E., Earl, D. L., Shively, K. M., McMillin, M. J., Smith, J. D., Turner, E. H., Stephan, M. J., Al-Gazali, L. I., Hertecant, J. L., Chitayat, D., Unger, S., Cohn, D. H., Krakow, D., Swanson, J. M., Faustman, E. M., Shendure, J., Nickerson, D. A., Bamshad, M. J., & University of Washington Center for Mendelian Genomics. (2013). Whole-genome analysis reveals that mutations in inositol polyphosphate phosphatase-like 1 cause opsismodysplasia. The American Journal of Human Genetics, 92(1), 137–143. https://doi.org/10.1016/j.ajhg.2012.11.011
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  9. Iida, A., Okamoto, N., Miyake, N., Nishimura, G., Minami, S., Sugimoto, T., Nakashima, M., Tsurusaki, Y., Saitsu, H., Shiina, M., Ogata, K., Watanabe, S., Ohashi, H., Matsumoto, N., & Ikegawa, S. (2013). Exome sequencing identifies a novel INPPL1 mutation in opsismodysplasia. Journal of Human Genetics, 58(6), 391–394. https://doi.org/10.1038/jhg.2013.25
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Kaynak Göster

APA
Bozlak, S., Yavaş, C., & Arvas, Y. E. (2026). A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia. Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 31. https://doi.org/10.53433/yyufbed.1981567
AMA
1.Bozlak S, Yavaş C, Arvas YE. A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia. YYUFBED. 2026;31. doi:10.53433/yyufbed.1981567
Chicago
Bozlak, Serdar, Cüneyd Yavaş, ve Yunus Emre Arvas. 2026. “A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia”. Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi 31 (Ekim). https://doi.org/10.53433/yyufbed.1981567.
EndNote
Bozlak S, Yavaş C, Arvas YE (01 Ekim 2026) A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia. Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi 31
IEEE
[1]S. Bozlak, C. Yavaş, ve Y. E. Arvas, “A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia”, YYUFBED, c. 31, Eki. 2026, doi: 10.53433/yyufbed.1981567.
ISNAD
Bozlak, Serdar - Yavaş, Cüneyd - Arvas, Yunus Emre. “A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia”. Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi 31 (01 Ekim 2026). https://doi.org/10.53433/yyufbed.1981567.
JAMA
1.Bozlak S, Yavaş C, Arvas YE. A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia. YYUFBED. 2026;31. doi:10.53433/yyufbed.1981567.
MLA
Bozlak, Serdar, vd. “A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia”. Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi, c. 31, Ekim 2026, doi:10.53433/yyufbed.1981567.
Vancouver
1.Serdar Bozlak, Cüneyd Yavaş, Yunus Emre Arvas. A Novel Synonymous Splice-Altering Variant in INPPL1 Expands the Mutational Spectrum of Opsismodysplasia. YYUFBED. 01 Ekim 2026;31. doi:10.53433/yyufbed.1981567