19-7560716-G-C

Variant names:

• chr19-7560716-G-C
• rs878854905
• NM_001166114.2:c.3768G>C

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP2

The NM_001166114.2(PNPLA6):​c.3768G>C​(p.Met1256Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,710 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: PNPLA6 NM_001166114.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.86
• Publications: 0 publications found

Genes affected

PNPLA6 (HGNC:16268): (patatin like phospholipase domain containing 6) This gene encodes a phospholipase that deacetylates intracellular phosphatidylcholine to produce glycerophosphocholine. It is thought to function in neurite outgrowth and process elongation during neuronal differentiation. The protein is anchored to the cytoplasmic face of the endoplasmic reticulum in both neurons and non-neuronal cells. Mutations in this gene result in autosomal recessive spastic paraplegia, and the protein is the target for neurodegeneration induced by organophosphorus compounds and chemical warfare agents. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2009]

PNPLA6 Gene-Disease associations (from GenCC):

• ataxia-hypogonadism-choroidal dystrophy syndrome

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, Orphanet
• PNPLA6-related spastic paraplegia with or without ataxia

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• retinal dystrophy-ataxia-pituitary hormone abnormality-hypogonadism syndrome

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• hereditary spastic paraplegia 39

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet
• cerebellar ataxia-hypogonadism syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Laurence-Moon syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• trichomegaly-retina pigmentary degeneration-dwarfism syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the PNPLA6 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 29 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. Gene score misZ: 4.3547 (above the threshold of 3.09). Trascript score misZ: 3.5139 (above the threshold of 3.09). GenCC associations: The gene is linked to retinal dystrophy-ataxia-pituitary hormone abnormality-hypogonadism syndrome, cerebellar ataxia-hypogonadism syndrome, PNPLA6-related spastic paraplegia with or without ataxia, ataxia-hypogonadism-choroidal dystrophy syndrome, trichomegaly-retina pigmentary degeneration-dwarfism syndrome, hereditary spastic paraplegia 39, Laurence-Moon syndrome.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PNPLA6	NM_001166114.2	c.3768G>C	p.Met1256Ile	missense_variant	Exon 29 of 32	ENST00000600737.6	NP_001159586.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PNPLA6	ENST00000600737.6	c.3768G>C	p.Met1256Ile	missense_variant	Exon 29 of 32	1	NM_001166114.2	ENSP00000473211.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461710 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727168

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53406

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111866

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000312 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary spastic paraplegia 39 Uncertain:1

May 18, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This sequence change replaces methionine, which is neutral and non-polar, with isoleucine, which is neutral and non-polar, at codon 1218 of the PNPLA6 protein (p.Met1218Ile). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with PNPLA6-related conditions. ClinVar contains an entry for this variant (Variation ID: 1517149). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on PNPLA6 protein function. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.75
BayesDel_addAF	Benign	-0.073	T
BayesDel_noAF	Benign	-0.34
CADD	Uncertain	25
DANN	Uncertain	0.99
Eigen	Benign	0.0031
Eigen_PC	Benign	0.19
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.98	.;D;D;D;D
M_CAP	Benign	0.019	T
MetaRNN	Uncertain	0.60	D;D;D;D;D
MetaSVM	Benign	-0.85	T
PhyloP100		9.9
PrimateAI	Uncertain	0.64	T
PROVEAN	Benign	-1.8	N;N;N;N;.
REVEL	Benign	0.27
Sift	Benign	0.16	T;T;T;T;.
Sift4G	Benign	0.37	T;T;T;T;T
Polyphen		0.016	B;.;.;B;.
Vest4		0.82
MVP		0.41
MPC		1.0
ClinPred		0.90	D
GERP RS		4.4
Varity_R		0.19
gMVP		0.59
Mutation Taster		=68/32	polymorphism

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

Other links and lift over

dbSNP: rs878854905; hg19: chr19-7625602;