chr8-22163875-C-A

Variant names:

• chr8-22163875-C-A
• rs2070687
• NM_001317778.2:c.436-26C>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001317778.2(SFTPC):​c.436-26C>A variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000692 in 1,445,006 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. There are indicators that this mutation may affect the branch point..

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: SFTPC NM_001317778.2 intron
• Scores: Splicing: ADA: 0.0003030
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.67
• Publications: 0 publications found

Genes affected

SFTPC (HGNC:10802): (surfactant protein C) This gene encodes the pulmonary-associated surfactant protein C (SPC), an extremely hydrophobic surfactant protein essential for lung function and homeostasis after birth. Pulmonary surfactant is a surface-active lipoprotein complex composed of 90% lipids and 10% proteins which include plasma proteins and apolipoproteins SPA, SPB, SPC and SPD. The surfactant is secreted by the alveolar cells of the lung and maintains the stability of pulmonary tissue by reducing the surface tension of fluids that coat the lung. Multiple mutations in this gene have been identified, which cause pulmonary surfactant metabolism dysfunction type 2, also called pulmonary alveolar proteinosis due to surfactant protein C deficiency, and are associated with interstitial lung disease in older infants, children, and adults. Alternatively spliced transcript variants encoding different protein isoforms have been identified.[provided by RefSeq, Feb 2010]

SFTPC Gene-Disease associations (from GenCC):

• surfactant metabolism dysfunction, pulmonary, 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae)
• chronic respiratory distress with surfactant metabolism deficiency

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• SFTPC- related interstitial lung disease

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: This position, referring to a specific DNA site, is a probable branch point but is likely benign (scored 1 / 10, using the threshold of <=3). The score ranges from 0 to 10, with values ≤3 considered benign and >5 classified as pathogenic. Computational evidence support a benign effect (BayesDel_noAF=-0.77).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SFTPC	NM_001317778.2	c.436-26C>A		intron_variant	Intron 4 of 5	ENST00000679463.1	NP_001304707.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SFTPC	ENST00000679463.1	c.436-26C>A		intron_variant	Intron 4 of 5		NM_001317778.2	ENSP00000505152.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.92e-7 AC: 1 AN: 1445006 Hom.: 0 Cov.: 29 AF XY: 0.00000139 AC XY: 1 AN XY: 719858

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33176

American (AMR) AF: 0.00 AC: 0 AN: 44656

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26028

East Asian (EAS) AF: 0.00 AC: 0 AN: 39622

South Asian (SAS) AF: 0.00 AC: 0 AN: 85918

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53082

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5750

European-Non Finnish (NFE) AF: 9.12e-7 AC: 1 AN: 1096988

Other (OTH) AF: 0.00 AC: 0 AN: 59786

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.77
CADD	Benign	11
DANN	Benign	0.53
PhyloP100		1.7
BranchPoint Hunter		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00030
dbscSNV1_RF	Benign	0.074
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs2070687; hg19: chr8-22021388;