rs1555573014

chr17-50191415-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 5P and 1B. PM1 PM2 PP2 BP4

The NM_000088.4(COL1A1):c.2203G>T(p.Ala735Ser) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A735V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: COL1A1 NM_000088.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.94

Genes affected

COL1A1 (HGNC:2197): (collagen type I alpha 1 chain) This gene encodes the pro-alpha1 chains of type I collagen whose triple helix comprises two alpha1 chains and one alpha2 chain. Type I is a fibril-forming collagen found in most connective tissues and is abundant in bone, cornea, dermis and tendon. Mutations in this gene are associated with osteogenesis imperfecta types I-IV, Ehlers-Danlos syndrome type VIIA, Ehlers-Danlos syndrome Classical type, Caffey Disease and idiopathic osteoporosis. Reciprocal translocations between chromosomes 17 and 22, where this gene and the gene for platelet-derived growth factor beta are located, are associated with a particular type of skin tumor called dermatofibrosarcoma protuberans, resulting from unregulated expression of the growth factor. Two transcripts, resulting from the use of alternate polyadenylation signals, have been identified for this gene. [provided by R. Dalgleish, Feb 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 3 uncertain in NM_000088.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, COL1A1
• BP4: Computational evidence support a benign effect (MetaRNN=0.4081635).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL1A1	NM_000088.4	c.2203G>T	p.Ala735Ser	missense_variant	32/51	ENST00000225964.10
COL1A1	XM_011524341.2	c.2005G>T	p.Ala669Ser	missense_variant	29/48
COL1A1	XM_005257058.5	c.2203G>T	p.Ala735Ser	missense_variant	32/49
COL1A1	XM_005257059.5	c.1285G>T	p.Ala429Ser	missense_variant	19/38

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL1A1	ENST00000225964.10	c.2203G>T	p.Ala735Ser	missense_variant	32/51	1	NM_000088.4	P1
COL1A1	ENST00000476387.1	n.552G>T		non_coding_transcript_exon_variant	8/9	2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Osteogenesis imperfecta type I Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 23, 2023

This sequence change replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 735 of the COL1A1 protein (p.Ala735Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with COL1A1-related conditions. ClinVar contains an entry for this variant (Variation ID: 456747). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt COL1A1 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.073
BayesDel_addAF	Uncertain	0.14	D
BayesDel_noAF	Uncertain	-0.030
Cadd	Uncertain	24
Dann	Uncertain	1.0
Eigen	Uncertain	0.20
Eigen_PC	Uncertain	0.32
FATHMM_MKL	Uncertain	0.93	D
M_CAP	Benign	0.065	D
MetaRNN	Benign	0.41	T
MetaSVM	Uncertain	0.37	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.53	T
PROVEAN	Benign	-1.4	N
REVEL	Uncertain	0.45
Sift	Benign	0.25	T
Sift4G	Benign	0.42	T
Vest4		0.44
MutPred		0.25		Gain of phosphorylation at A735 (P = 0.0058);
MVP		0.76
MPC		1.1
ClinPred		0.75	D
GERP RS		5.6
gMVP		0.60

Splicing

Name	Calibrated prediction	Score	Prediction
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

Publications

LitVar

Other links and lift over

dbSNP: rs1555573014; hg19: chr17-48268776;