NM_006412.4:c.493-1G>C

Variant names:

• chr9-136676681-C-G
• rs606231168
• NM_006412.4:c.493-1G>C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_006412.4(AGPAT2):​c.493-1G>C variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.00000186 in 1,613,232 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: AGPAT2 NM_006412.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 6.87

Genes affected

AGPAT2 (HGNC:325): (1-acylglycerol-3-phosphate O-acyltransferase 2) This gene encodes a member of the 1-acylglycerol-3-phosphate O-acyltransferase family. The protein is located within the endoplasmic reticulum membrane and converts lysophosphatidic acid to phosphatidic acid, the second step in de novo phospholipid biosynthesis. Mutations in this gene have been associated with congenital generalized lipodystrophy (CGL), or Berardinelli-Seip syndrome, a disease characterized by a near absence of adipose tissue and severe insulin resistance. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.11469534 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.1, offset of 7, new splice context is: cctctccctgcacctcaaAGtgt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-136676681-C-G is Pathogenic according to our data. Variant chr9-136676681-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 6630.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
AGPAT2	NM_006412.4	c.493-1G>C		splice_acceptor_variant, intron_variant	Intron 3 of 5	ENST00000371696.7	NP_006403.2
AGPAT2	NM_001012727.2	c.492+280G>C		intron_variant	Intron 3 of 4		NP_001012745.1
AGPAT2	XM_047422636.1	c.184-1G>C		splice_acceptor_variant, intron_variant	Intron 3 of 5		XP_047278592.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
AGPAT2	ENST00000371696.7	c.493-1G>C		splice_acceptor_variant, intron_variant	Intron 3 of 5	1	NM_006412.4	ENSP00000360761.2
AGPAT2	ENST00000371694.7	c.492+280G>C		intron_variant	Intron 3 of 4	1		ENSP00000360759.3
AGPAT2	ENST00000472820.1	n.421-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 3	1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152208 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250564 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135758

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461024 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726808

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152208 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74352

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Congenital generalized lipodystrophy type 1 Pathogenic:3 Other:1

Feb 05, 2022

DASA

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.493-1G>C variant is located in a canonical splice-site, and it is not predicted the protein reading frame alteration, however, occur in a critical region and the variant disrupts <10% of protein - PVS1_moderate. This sequence change has been observed in affected individual(s) and ClinVar contains an entry for this variant (ClinVar ID: 6630; PMID: 24498038, 15181077) - PS4_supporting. The variant is present at low allele frequencies population databases (rs606231168 – gnomAD 0.00006570%; ABraOM no frequency - http://abraom.ib.usp.br/) - PM2_supporting. The c.493-1G>C was detected in trans with a pathogenic variant (PMID: 24498038) - PM3. In summary, the currently available evidence indicates that the variant is likely pathogenic. -

Mar 04, 2013

Unidad de Genómica Médica UC, Pontificia Universidad Católica de Chile

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder characterized by extreme reduction of white adipose tissue (WAT) mass. CGL type 1 is the most frequent form and is caused by mutations in AGPAT2. Genetic and clinical studies were performed in two affected sisters of a Chilean family. These patients have notoriously dissimilar metabolic abnormalities that correlate with differential levels of circulating leptin and soluble leptin receptor fraction. Sequencing of AGPAT2 exons and exon-intron boundaries revealed two homozygous mutations in both sisters. Intronic c.493-1G>C mutation destroy a conserved splicing site that likely leads to exon 4 skipping and deletion of whole AGPAT2 substrate binding domain. In silico protein modeling provided insights of the mechanisms of lack of catalytic activity owing to both mutations. -

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GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Jun 01, 2004

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.15
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Uncertain	0.95	D
GERP RS		3.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.45		Position offset: -8
DS_AL_spliceai		0.99		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs606231168; hg19: chr9-139571133;