rs587778809

Variant names:

• chr4-127938781-A-T
• rs587778809
• NM_001371596.2:c.754+2T>A

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_001371596.2(MFSD8):​c.754+2T>A variant causes a splice donor, intron change. The variant allele was found at a frequency of 0.0000162 in 1,606,642 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 0.000033 (0 hom., cov: 31)
  • Exomes 𝑓: 0.000014 (0 hom.)
• Consequence: MFSD8 NM_001371596.2 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7
• Conservation: PhyloP100: 6.69
• Publications: 12 publications found

Genes affected

MFSD8 (HGNC:28486): (major facilitator superfamily domain containing 8) This gene encodes a ubiquitous integral membrane protein that contains a transporter domain and a major facilitator superfamily (MFS) domain. Other members of the major facilitator superfamily transport small solutes through chemiosmotic ion gradients. The substrate transported by this protein is unknown. The protein likely localizes to lysosomal membranes. Mutations in this gene are correlated with a variant form of late infantile-onset neuronal ceroid lipofuscinoses (vLINCL). [provided by RefSeq, Oct 2008]

MFSD8 Gene-Disease associations (from GenCC):

• neuronal ceroid lipofuscinosis

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• neuronal ceroid lipofuscinosis 7

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet, G2P
• macular dystrophy with central cone involvement

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 4-127938781-A-T is Pathogenic according to our data. Variant chr4-127938781-A-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 65897.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
MFSD8	NM_001371596.2	c.754+2T>A		splice_donor_variant, intron_variant	Intron 7 of 11	ENST00000641686.2	NP_001358525.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MFSD8	ENST00000641686.2	c.754+2T>A		splice_donor_variant, intron_variant	Intron 7 of 11		NM_001371596.2	ENSP00000493218.2

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 151996 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000735

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000798 AC: 2 AN: 250734 AF XY: 0.0000148

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000291

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000882

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000144 AC: 21 AN: 1454646 Hom.: 0 Cov.: 28 AF XY: 0.0000207 AC XY: 15 AN XY: 724082

African (AFR) AF: 0.00 AC: 0 AN: 33332

American (AMR) AF: 0.0000224 AC: 1 AN: 44592

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26008

East Asian (EAS) AF: 0.00 AC: 0 AN: 39426

South Asian (SAS) AF: 0.00 AC: 0 AN: 85850

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53220

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5738

European-Non Finnish (NFE) AF: 0.0000181 AC: 20 AN: 1106410

Other (OTH) AF: 0.00 AC: 0 AN: 60070

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 151996 Hom.: 0 Cov.: 31 AF XY: 0.0000404 AC XY: 3 AN XY: 74262

African (AFR) AF: 0.00 AC: 0 AN: 41400

American (AMR) AF: 0.00 AC: 0 AN: 15268

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10532

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000735 AC: 5 AN: 67984

Other (OTH) AF: 0.00 AC: 0 AN: 2084

Alfa AF: 0.0000752 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neuronal ceroid lipofuscinosis 7 Pathogenic:4

Dec 24, 2018

Centre for Mendelian Genomics, University Medical Centre Ljubljana

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was classified as: Pathogenic. The following ACMG criteria were applied in classifying this variant: PVS1,PM2,PP3,PP5. -

Aug 01, 2013

GeneReviews

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: curation

- -

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The MFSD8 c.754+2T>A variant occurs in a canonical splice donor site and is therefore predicted to disrupt or distort the normal gene product. The variant has been reported in four studies and found in a total of 12 individuals with confirmed or suspected neuronal ceroid-lipofuscinosis, including in eight individuals (including two siblings) in a homozygous state and in four individuals in a compound heterozygous state (Siintola et al. 2007; Kousi et al. 2009; Kousi et al. 2011; Craiu et al. 2015). The c.754+2T>A variant was also reported in a heterozygous state in one unaffected parent. The variant was absent from 504 control chromosomes and not found in the 1000 Genomes Project, the Exome Sequencing Project, or the Exome Aggregation Consortium. RT-PCR showed aberrant splicing of the variant mRNA leading to an altered pattern of products including almost complete loss of the normal transcript containing exons 7-10 of the gene (Siintola et al. 2007). Based on potential impact of splice donor variants and the evidence from the literature, the c.754+2T>A variant is classified as pathogenic for neuronal ceroid-lipofuscinosis. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Feb 19, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 8 of the MFSD8 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in MFSD8 are known to be pathogenic (PMID: 19177532, 25227500, 28586915). This variant is present in population databases (rs587778809, gnomAD 0.003%). Disruption of this splice site has been observed in individuals with MFSD8-related conditions (PMID: 17564970, 19201763, 25439737). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 65897). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Macular dystrophy with central cone involvement Pathogenic:1

Jan 30, 2021

Institute of Medical Molecular Genetics, University of Zurich

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Late-infantile neuronal ceroid lipofuscinosis Pathogenic:1

Sep 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not provided Pathogenic:1

Jul 08, 2022

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Canonical splice site variant predicted to result in a null allele in a gene for which loss-of-function is a known mechanism of disease; Not observed at a significant frequency in large population cohorts (gnomAD); A different variant affecting the same splice site (c.754+1G>A) has been reported in association with late infantile neuronal ceroid lipofuscinosis (Kousi et al., 2012); This variant is associated with the following publications: (PMID: 25525159, 19277732, 25439737, 31589614, 17564970) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Uncertain	0.12
CADD	Pathogenic	29
DANN	Uncertain	0.99
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		6.7
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=6/94	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.72		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.72		Position offset: 2

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

Other links and lift over

dbSNP: rs587778809; hg19: chr4-128859936;