NM_001317778.2:c.218T>C
Variant summary
Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1PM2PP5_Very_Strong
The NM_001317778.2(SFTPC):c.218T>C(p.Ile73Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,844 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★).
Frequency
Consequence
NM_001317778.2 missense
Scores
Clinical Significance
Conservation
Publications
- surfactant metabolism dysfunction, pulmonary, 2Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae)
- chronic respiratory distress with surfactant metabolism deficiencyInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- SFTPC- related interstitial lung diseaseInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Pathogenic. The variant received 12 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| SFTPC | NM_001317778.2 | c.218T>C | p.Ile73Thr | missense_variant | Exon 3 of 6 | ENST00000679463.1 | NP_001304707.1 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| SFTPC | ENST00000679463.1 | c.218T>C | p.Ile73Thr | missense_variant | Exon 3 of 6 | NM_001317778.2 | ENSP00000505152.1 |
Frequencies
GnomAD3 genomes Cov.: 33
GnomAD2 exomes AF: 0.00 AC: 0AN: 249478 AF XY: 0.00
GnomAD4 exome AF: 0.00000274 AC: 4AN: 1461844Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1AN XY: 727230 show subpopulations
Age Distribution
GnomAD4 genome Cov.: 33
ClinVar
Submissions by phenotype
Surfactant metabolism dysfunction, pulmonary, 2 Pathogenic:9
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The p.Ile73Thr variant has been previously reported in patients affected with interstitial lung disease (Liu et al, 2019). This previously reported SFTPC variant results in mistrafficking of the SFTPC pre-protein and has been identified in multiple individuals with surfactant protein C deficiency. This variant has been reported to the ClinVar database as Pathogenic. This variant is novel (not in any individuals) in 1000 Genomes. The amino acid Ile at position 73 is changed to a Thr changing protein sequence and it might alter its composition and physico-chemical properties. The variant is predicted to be damaging by both SIFT and PolyPhen2. The residue is conserved across species. The amino acid change p.Ile73Thr in SFTPC is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. For these reasons, this variant has been classified as Pathogenic -
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This previously reported SFTPC variant results in mistrafficking of the SFTPC pre-protein and has been identified in multiple individuals with surfactant protein C deficiency. We consider this variant to be pathogenic. -
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The variant is not observed in the gnomAD v2.1.1 dataset. Predicted Consequence/Location: Missense variant Functional studies provide moderate evidence of the variant having a damaging effect on the gene or gene product (PMID: 21092132). In silico tool predictions suggest the damaging effect of the variant on the gene or gene product (REVEL: 0.73; 3Cnet: 0.37). The same nucleotide change resulting in the same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000013208 /PMID: 11893657).A different missense change at the same codon (p.Ile73Asn) has been reported to be associated with SFTPC related disorder (PMID: 31081264). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
not provided Pathogenic:3
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This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 73 of the SFTPC protein (p.Ile73Thr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with childhood interstitial lung disease (PMID: 15293602, 15572558, 15756222). In at least one individual the variant was observed to be de novo. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 13208). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Experimental studies have shown that this missense change affects SFTPC function (PMID: 21707890). For these reasons, this variant has been classified as Pathogenic. -
Published functional studies demonstrate damaging effects including impaired uptake and degradation of surfactant phospholipid and accumulation of dysfunctional mitochondria (PMID: 21707890, 25344067); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 22461427, 26925580, 15572558, 32851322, 21707890, 25582472, 11893657, 25344067, 18643778, 21092132, 25553246, 20371530, 23701443, 15756222, 23926107, 25755194, 17597647, 15293602, 29569581, 31081264, 30630227, 31462320, 32095252, 28495692, 34134972, 33942430) -
Pulmonary fibrosis Pathogenic:1
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Hereditary pulmonary alveolar proteinosis Pathogenic:1
The c.218T>C (p.I73T) alteration is located in exon 3 (coding exon 3) of the SFTPC gene. This alteration results from a T to C substitution at nucleotide position 218, causing the isoleucine (I) at amino acid position 73 to be replaced by a threonine (T). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This mutation is considered to account for approximately 30% of described mutations in the SFTPC gene. It was described in a large kindred with multiple individuals to co-segregate with lung disease of variable severity (Cameron, 2005) and has been reported as a de novo occurrence in several unrelated patients (Guillot, 2009). This amino acid position is not well conserved in available vertebrate species. In vitro studies have demonstrated that this alteration interferes with correct processing and routing of the final protein, as well as reduction in lipid degradation (Beers, 2011). The in silico prediction for this alteration is inconclusive. Based on the available evidence, this alteration is classified as pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at