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Gene

SPR

sepiapterin reductase

Summary

Cytogenetic location
2p13.2
Coordinates
Chromosome 2: 72,887,408–72,892,158 (GRCh38)
Exons
3 exons across 4.8 kb
Protein
261 amino acids
Inheritance
Autosomal recessive
Also known as
SDR38C1
MANE Select transcript
ENST00000234454.6NM_003124.5
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

  • BH4 Deficiency & Monoamine Neurotransmitter Disorders

    • Sepiapterin Reductase DeficiencyAutosomal recessive

      Caused by variants in SPR, which reduce dopamine and serotonin and cause movement problems, fluctuating weakness and developmental delay, without raised phenylalanine.

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

      Knowing allows treatment with L-dopa and 5-hydroxytryptophan, which can markedly improve symptoms.

    • Hyperphenylalaninemia due to BH4 DeficiencyAutosomal recessive

      Caused by variants in PTS, QDPR, PCBD1 or GCH1, which raise phenylalanine and reduce dopamine and serotonin, leading to movement problems, seizures and developmental delay.

      • 1 GenCC submitter rates it definitive or strong
      What knowing changes

      Knowing allows treatment with BH4, neurotransmitter precursors (L-dopa, 5-hydroxytryptophan) and folinic acid where needed.

  • Dystonia, Myotonia, Paroxysmal Dyskinesia

    • Inherited Dystonia

      Umbrella term covering inherited dystonias, including DYT-TOR1A early-onset generalized dystonia, DYT-THAP1, myoclonus-dystonia (SGCE) and KMT2B-related dystonia.

      • ClinGen rates the link definitive
      • 5 GenCC submitters rate it definitive or strong

Inheritance

Autosomal recessive
It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.

How SPR is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome 2, with a bracket where SPR sits. SPR and 11 genes near it on chromosome 2, from 72,389,783 to 73,389,782.Chromosome 22p13.2p25.3p25.2p25.1p24.3p24.2p24.1p23.3p23.2p23.1p22.3p22.2p22.1p21p16.3p16.2p16.1p15p14p13.3p13.2p13.1p12p11.2p11.1q11.1q11.2q12.1q12.2q12.3q13q14.1q14.2q14.3q21.1q21.2q21.3q22.1q22.2q22.3q23.1q23.2q23.3q24.1q24.2q24.3q31.1q31.2q31.3q32.1q32.2q32.3q33.1q33.2q33.3q34q35q36.1q36.2q36.3q37.1q37.2q37.372.4 Mb72.6 Mb72.8 Mb73 Mb73.2 MbEXOC6B: 72,170,079–72,826,055, reverse strandEXOC6BSPR: 72,887,408–72,892,158, forward strandSPREMX1: 72,916,184–72,936,071, forward strandEMX1SFXN5: 72,939,248–73,075,619, reverse strandSFXN5RAB11FIP5: 73,073,382–73,156,721, reverse strandRAB11FIP5NOTO: 73,202,570–73,212,513, forward strandNOTOSMYD5: 73,214,222–73,227,229, forward strandSMYD5PRADC1: 73,228,008–73,233,262, reverse strandPRADC1CCT7: 73,233,420–73,253,282, forward strandCCT7FBXO41: 73,254,682–73,284,478, reverse strandFBXO41EGR4: 73,290,927–73,293,721, reverse strandEGR4ALMS1: 73,385,758–73,625,166, forward strandALMS1Diagram of SPR: 3 exons on the forward strand of chromosome 2Exon 1: 10 known disease-causing sitesExon 2: 6 known disease-causing sitesExon 3: 8 known disease-causing sitesExon 1: 72,887,408–72,887,736, 329 basesExon 2: 72,888,314–72,888,604, 291 basesExon 3: 72,891,347–72,892,158, 812 bases1235′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 1.4 kb of the gene's 4.8 kb; 786 of those bases code for the protein.

How a genome test reads SPR

26

positions in SPR 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 4.8 kb of SPR, introns included, not only the 1.4 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.). SPR gene: sepiapterin reductase. Retrieved 16 October 2026, from https://dantelabs.com/genes/spr

Vancouver

Dante Labs. SPR gene: sepiapterin reductase [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/spr

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