chr6-36270669-G-A

Position:

• chr6-36270669-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_001374623.1(PNPLA1):​c.205+5G>A variant causes a splice donor 5th base, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: PNPLA1 NM_001374623.1 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 5.10

Genes affected

PNPLA1 (HGNC:21246): (patatin like phospholipase domain containing 1) The protein encoded by this gene belongs to the patatin-like phospholipase (PNPLA) family, which is characterized by the presence of a highly conserved patatin domain. PNPLA family members have diverse lipolytic and acyltransferase activities, and are key elements in lipid metabolism. While other members of this family have been well characterized, the function of this gene remained an enigma. However, recent studies show that this gene is expressed in the skin epidermal keratinocytes, and has a role in glycerophospholipid metabolism in the cutaneous barrier. Consistent with these observations, mutations in this gene are associated with ichthyosis in human (autosomal recessive congenital ichthyoses, ARCI) and dog. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jun 2012]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 6-36270669-G-A is Pathogenic according to our data. Variant chr6-36270669-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 633800.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PNPLA1	NM_001374623.1	c.205+5G>A		splice_donor_5th_base_variant, intron_variant		ENST00000636260.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PNPLA1	ENST00000636260.2	c.205+5G>A		splice_donor_5th_base_variant, intron_variant		5	NM_001374623.1	A2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Lamellar ichthyosis Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jan 12, 2024

Variant summary: PNPLA1 c.205+5G>A alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: four predict the variant abolishes a 5' splicing donor site. One publication reported whole transcriptome analysis from a skin biopsy sample of a homozygous patient, and found the was absence of PNPLA1 transcript as compared to age- and sex-matched controls, suggesting that the absence of transcript could be caused by nonsense mediated decay (NMD) or other mechanisms leading to transcript instability (Youssefian_2019). The variant was absent in 151370 control chromosomes (gnomAD). c.205+5G>A has been reported in the literature in a homozygous individual affected with Lamellar Ichthyosis (Youssefian_2019, Uitto_2020, Youssefian_2021). These data indicate that the variant may be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 30578701, 32147742, 33969388). ClinVar contains an entry for this variant (Variation ID: 633800). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Autosomal recessive congenital ichthyosis 10 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Uitto Lab, Thomas Jefferson University

Jun 08, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.37
CADD	Pathogenic	27
DANN	Benign	0.94

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.11		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: rs1561853887; hg19: chr6-36238446;