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Gene

SMPX

small muscle protein X-linked

Summary

Cytogenetic location
Xp22.12
Coordinates
Chromosome X: 21,705,978–21,758,116 (GRCh38)
Exons
5 exons across 52.1 kb
Protein
88 amino acids
Also known as
DFNX4, Chisel, Csl
Previous symbols
DFN6
MANE Select transcript
ENST00000379494.4NM_014332.3
Locus type
gene with protein product
  • Very high
  • Confident
  • Low
  • Very low

Reference genomeGRCh38

Positions on gene and variant pages follow this choice, in this browser.

Curated reports relevant to this gene

  • Distal Myopathies

    • Distal myopathy

      A group of inherited muscle disorders in which weakness starts in the hands, forearms, lower legs or feet, caused by genes such as TTN, DYSF, FLNC, MYH7, ADSS1, SMPX and MATR3.

      • 2 GenCC submitters rate it definitive or strong

Broader groupings

  • Hearing Loss and Deafness

    • Nonsyndromic Genetic Hearing Loss

      One of 97 genes linked to it

      Inherited hearing loss without other medical features, including the common recessive forms caused by GJB2, OTOF, SLC26A4, STRC and many other genes, as well as dominant, X-linked and mitochondrial forms.

      • ClinGen rates the link definitive
      • 3 GenCC submitters rate it definitive or strong
      What knowing changes

      Knowing the genetic cause can guide hearing support and cochlear implant decisions, gene-therapy trial eligibility (for example OTOF) and family counselling.

How SMPX is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome X, with a bracket where SMPX sits. SMPX and 6 genes near it on chromosome X, from 21,232,047 to 22,232,046.Chromosome XXp22.12p22.33p22.32p22.31p22.2p22.13p22.12p22.11p21.3p21.2p21.1p11.4p11.3p11.23p11.22p11.21p11.1q11.1q11.2q12q13.1q13.2q13.3q21.1q21.2q21.31q21.32q21.33q22.1q22.2q22.3q23q24q25q26.1q26.2q26.3q27.1q27.2q27.3q2821.4 Mb21.6 Mb21.8 Mb22 Mb22.2 MbCNKSR2: 21,372,801–21,654,701, forward strandCNKSR2KLHL34: 21,654,690–21,658,330, reverse strandKLHL34SMPX: 21,705,978–21,758,116, reverse strandSMPXMBTPS2: 21,839,600–21,935,555, forward strandMBTPS2YY2: 21,855,987–21,858,740, forward strandYY2SMS: 21,940,557–21,994,837, forward strandSMSPHEX: 22,032,293–22,494,713, forward strandPHEXDiagram of SMPX: 5 exons on the reverse strand of chromosome XExon 4: 3 known disease-causing sitesExon 3: 1 known disease-causing siteExon 2: 1 known disease-causing siteExon 5: 21,705,978–21,706,394, 417 basesExon 4: 21,737,549–21,737,697, 149 basesExon 3: 21,743,750–21,743,836, 87 basesExon 2: 21,754,246–21,754,302, 57 basesExon 1: 21,757,942–21,758,116, 175 bases543215′3′

Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.

Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).

Nearby genes from Ensembl release 116, on GRCh38.

Exons make up 0.9 kb of the gene's 52.1 kb; 267 of those bases code for the protein.

How a genome test reads SMPX

6

positions in SMPX where ClinVar classes a change as pathogenic or likely pathogenic

None of them falls in a region short reads find hard.

A whole genome covers all 52.1 kb of SMPX, introns included, not only the 0.9 kb of exons.

Where this comes from

  • HGNC: the gene's symbol, name, other symbols and location.
  • MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
  • GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
  • The ACMG secondary findings list, SF v3.2.
  • ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
  • The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
  • Data release 2026.10.16-c6eea6bf.

Cite this page

APA

Dante Labs. (n.d.). SMPX gene: small muscle protein X-linked. Retrieved 16 October 2026, from https://dantelabs.com/genes/smpx

Vancouver

Dante Labs. SMPX gene: small muscle protein X-linked [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/smpx

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