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SUMF1
sulfatase modifying factor 1
SUMF1 is located on the short (p) arm of chromosome 3, at band 3p26.1. Arm ratio per GRCh38 - banding schematic.
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Overview
SUMF1 (sulfatase modifying factor 1) is located on chromosome 3p26.1 and encodes formylglycine-generating enzyme (FGE), a critical protein that activates all sulfatase enzymes in human cells. The gene produces a 374-amino-acid enzyme that operates within the endoplasmic reticulum, where newly synthesised proteins are processed before distribution throughout the cell.
Sulfatases represent a family of enzymes that cleave sulfate groups from various biological molecules, enabling their breakdown and recycling. Because FGE is required to activate every sulfatase enzyme, pathogenic variants in SUMF1 simultaneously impair multiple metabolic pathways. This unique position makes SUMF1 essential for normal development and cellular function, and its dysfunction results in the accumulation of sulfate-containing compounds across multiple tissues.
What the gene does
Formylglycine-generating enzyme performs a highly specific post-translational modification that is absolutely required for sulfatase activity. The enzyme converts a cysteine residue within the active site of sulfatase proteins into a specialised amino acid derivative called C-alpha-formylglycine (formylglycine). This chemical modification creates the catalytic centre that allows sulfatases to remove sulfate groups from their target molecules.
Without this modification, sulfatases remain enzymatically inactive despite being correctly synthesised and folded. FGE operates in the endoplasmic reticulum, intercepting newly made sulfatases before they reach their final cellular destinations. The enzyme recognises a conserved sequence motif present in all sulfatase family members, ensuring comprehensive activation of these degradative enzymes. Sulfatases themselves participate in breaking down glycosaminoglycans, sulfolipids, steroid sulfates, and other sulfated compounds essential for skeletal development, hormone regulation, and extracellular matrix turnover.
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Chromosome location
SUMF1 is positioned on the short arm of chromosome 3 at band p26.1, a region near the chromosome's terminus. The gene spans genomic DNA encoding the 374-amino-acid formylglycine-generating enzyme. This chromosomal location places SUMF1 within a gene-dense region containing multiple developmental and metabolic regulators.
Protein structure
The SUMF1-encoded protein comprises 374 amino acids with defined functional regions that facilitate its role in sulfatase activation. A disordered region spans amino acids 61-84, likely providing structural flexibility during substrate recognition. The interaction with sulfatases occurs through a region encompassing amino acids 341-360, representing the portion of FGE that directly binds to sulfatase substrates to enable the cysteine-to-formylglycine conversion. This C-terminal positioning of the sulfatase-binding region allows the enzyme to engage with the conserved motifs present across all sulfatase family members.
Key variants
More than 35 pathogenic variants in SUMF1 have been identified in individuals with multiple sulfatase deficiency. The majority of disease-causing changes are missense variants that substitute single amino acids within the FGE enzyme, severely compromising its ability to modify sulfatases. These alterations typically reduce or abolish formylglycine-generating activity, leading to globally decreased sulfatase function. The spectrum of variants ranges from those causing near-complete loss of enzyme activity to those retaining residual function, contributing to variability in disease severity and age of onset.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.1046G>C | p.Arg349Pro | Pathogenic/Likely pathogenic | ★★☆☆ | Spinocerebellar ataxia type 15/16 |
c.536G>A | p.Trp179Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.603-2del | - | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.670C>T | p.Arg224Trp | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.778_779delinsCTTGCTCATACTCGCC | p.Ile260fs | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.790G>T | p.Glu264Ter | Pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.817G>A | p.Asp273Asn | Pathogenic/Likely pathogenic | ★★☆☆ | SUMF1-related disorder |
c.832del | p.Thr278fs | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.940G>T | p.Glu314Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
c.955-3_970del | - | Pathogenic/Likely pathogenic | ★★☆☆ | Multiple sulfatase deficiency |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Pathogenic variants in SUMF1 cause multiple sulfatase deficiency, a rare autosomal recessive metabolic disorder characterised by the simultaneous impairment of all sulfatase enzymes. This condition typically presents at birth or in early childhood with progressive neurological decline, developmental regression, and distinctive physical features including coarse facial appearance, skeletal abnormalities, and ichthyosis (scaly, thickened skin). The accumulated sulfate-containing substrates affect the brain, liver, skeleton, and skin, leading to a multisystem disorder with variable severity depending on the degree of residual FGE activity.
UK clinical status
SUMF1 holds green (high-evidence) status across multiple NHS Genomic Medicine Service gene panels, reflecting strong clinical validity for genetic testing in diverse presentations. The gene appears on the DDG2P developmental disorders panel, the lysosomal storage disorder panel (R276), and the likely inborn error of metabolism panel (R98), consistent with its role in a metabolic disease affecting development. Green classification on the inherited white matter disorders panel, intellectual disability panel (R29), and skeletal dysplasia panel (R104) reflects the multisystem nature of multiple sulfatase deficiency. Additional inclusion on the foetal anomalies (R21), hydrocephalus (R86), and retinal disorders (R32) panels indicates that SUMF1-related disease may present with congenital abnormalities detectable prenatally or in infancy.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
How does SUMF1 differ from other lysosomal storage disorder genes?
Unlike genes encoding individual lysosomal enzymes, SUMF1 encodes an activator enzyme required for the function of an entire enzyme family. Pathogenic variants in SUMF1 therefore impair multiple metabolic pathways simultaneously, producing a combined phenotype that overlaps several distinct lysosomal storage disorders.
Can individuals with SUMF1 variants have milder symptoms?
Disease severity in multiple sulfatase deficiency depends on the degree of residual formylglycine-generating enzyme activity. Some variants allow partial enzyme function, leading to later onset and slower progression compared to variants causing near-complete loss of activity. Clinical presentation ranges from severe neonatal forms to attenuated juvenile-onset disease.
Is genetic testing for SUMF1 available through the NHS?
Yes, SUMF1 is included on multiple NHS Genomic Medicine Service panels with green (high-evidence) ratings, making testing available through appropriate clinical referral pathways for individuals with suspected lysosomal storage disorders, unexplained developmental regression, or skeletal dysplasia with neurological features.
References
- Schlotawa L, Radhakrishnan K, Baumgartner M. Rapid degradation of an active formylglycine generating enzyme variant leads to a late infantile severe form of multiple sulfatase deficiency. European journal of human genetics : EJHG. 2013. PMID: 23321616
- Schlotawa L, Ennemann EC, Radhakrishnan K. SUMF1 mutations affecting stability and activity of formylglycine generating enzyme predict clinical outcome in multiple sulfatase deficiency. European journal of human genetics : EJHG. 2011. PMID: 21224894
- Schlotawa L, Steinfeld R, von Figura K. Molecular analysis of SUMF1 mutations: stability and residual activity of mutant formylglycine-generating enzyme determine disease severity in multiple sulfatase deficiency. Human mutation. 2008. PMID: 18157819
- Annunziata I, Bouchè V, Lombardi A. Multiple sulfatase deficiency is due to hypomorphic mutations of the SUMF1 gene. Human mutation. 2007. PMID: 17657823
- Dierks T, Dickmanns A, Preusser-Kunze A. Molecular basis for multiple sulfatase deficiency and mechanism for formylglycine generation of the human formylglycine-generating enzyme. Cell. 2005. PMID: 15907468
- Cosma MP, Pepe S, Parenti G. Molecular and functional analysis of SUMF1 mutations in multiple sulfatase deficiency. Human mutation. 2004. PMID: 15146462
- Dierks T, Schmidt B, Borissenko LV. Multiple sulfatase deficiency is caused by mutations in the gene encoding the human C(alpha)-formylglycine generating enzyme. Cell. 2003. PMID: 12757705
- Cosma MP, Pepe S, Annunziata I. The multiple sulfatase deficiency gene encodes an essential and limiting factor for the activity of sulfatases. Cell. 2003. PMID: 12757706