rs749708827

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000153.4(GALC):c.1896_1900delCACGT(p.Thr633AsnfsTer3) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000236 in 1,606,990 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. L632L) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000025 ( 0 hom. )

Consequence

GALC
NM_000153.4 frameshift

Scores

Not classified

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5

Conservation

PhyloP100: 3.13

Publications

0 publications found

Variant links:

Genes affected

GALC (HGNC:4115): (galactosylceramidase) This gene encodes a lysosomal protein which hydrolyzes the galactose ester bonds of galactosylceramide, galactosylsphingosine, lactosylceramide, and monogalactosyldiglyceride. Mutations in this gene have been associated with Krabbe disease, also known as globoid cell leukodystrophy. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. [provided by RefSeq, Jul 2008]

GALC Gene-Disease associations (from GenCC):

Krabbe disease
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Myriad Women’s Health, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), PanelApp Australia, ClinGen, Genomics England PanelApp

GALC links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

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

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. There are 28 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 14-87939915-AACGTG-A is Pathogenic according to our data. Variant chr14-87939915-AACGTG-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 555939.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
GALC	NM_000153.4 link	c.1896_1900delCACGT	p.Thr633AsnfsTer3	frameshift_variant	Exon 16 of 17	ENST00000261304.7	NP_000144.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GALC	ENST00000261304.7 link	c.1896_1900delCACGT	p.Thr633AsnfsTer3	frameshift_variant	Exon 16 of 17	1	NM_000153.4	ENSP00000261304.2

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

151952

Hom.:

Cov.:

show subpopulations

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000402

AC:

AN:

248814

AF XY:

0.00000741

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000887

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000254

AC:

AN:

1455038

Hom.:

AF XY:

0.0000235

AC XY:

AN XY:

724350

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33264

American (AMR)

AF:

0.00

AC:

AN:

44636

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26008

East Asian (EAS)

AF:

0.00

AC:

AN:

39618

South Asian (SAS)

AF:

0.00

AC:

AN:

86098

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53286

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5744

European-Non Finnish (NFE)

AF:

0.0000316

AC:

AN:

1106332

Other (OTH)

AF:

0.0000333

AC:

AN:

60052

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000000000074607), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.379

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00000658

AC:

AN:

151952

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74210

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41416

American (AMR)

AF:

0.00

AC:

AN:

15220

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5172

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

67898

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000113

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Galactosylceramide beta-galactosidase deficiency

Pathogenic:4

Feb 04, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Thr633Asnfs*3) in the GALC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 53 amino acid(s) of the GALC protein. For these reasons, this variant has been classified as Pathogenic. This variant disrupts a region of the GALC protein in which other variant(s) (p.Leu634Ser) have been determined to be pathogenic (PMID: 9272171, 16607461, 24252386, 26865610, 27679535, 27780934). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. Experimental studies have shown that this premature translational stop signal affects GALC function (PMID: 27638593). Algorithms developed to predict the effect of variants on protein structure and function are not available or were not evaluated for this variant. ClinVar contains an entry for this variant (Variation ID: 555939). This variant is also known as c.1848_1852del. This premature translational stop signal has been observed in individual(s) with Krabbe disease (PMID: 21824559). This variant is present in population databases (rs749708827, gnomAD 0.0009%). -

Dec 02, 2021

Molecular Genetics, Royal Melbourne Hospital

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change in GALC is a frameshift variant that may cause a premature stop codon, p.(Thr633Asnfs*3), that is predicted to escape nonsense mediated decay and remove <10% of the protein, however it is a truncation of a functionally important region in a gene where loss-of-function is an established disease mechanism (PMID: 27638593). This variant is present in a single individual in gnomAD v2.1 (1/112,760 alleles) in the European (non-Finnish) population. This variant has been detected in at least two individuals with Krabbe disease and deficient GALC activity. Both were compound heterozygous for the variant and a pathogenic variant and one of those were confirmed in trans by parental testing (PMID: 21824559, 22704718). RMH ACMG Guidelines v1.5.1, this variant is classified as LIKELY PATHOGENIC. Following criteria are met: PVS1_Strong, PM3, PM2_Supporting, PP4. -

Aug 17, 2020

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

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: GALC c.1896_1900delCACGT (p.Thr633AsnfsX3) results in a premature termination codon, predicted to cause a truncation of the encoded protein. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant allele was found at a frequency of 4e-06 in 248814 control chromosomes. c.1896_1900delCACGT has been reported in the literature in individuals affected with Krabbe Disease (Duffner_2011, Tanner_2012). These data indicate that the variant may be associated with disease. At least one publication reported experimental evidence evaluating an impact on protein function, and demonstrated almost complete loss of activity for the truncated protein (Saavedra-Matiz_2016). One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and classified the variant as likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Jan 04, 2018

Counsyl

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

not provided

Pathogenic:1

Jul 26, 2019

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Frameshift variant in the C-terminus predicted to result in protein truncation, as the last 53 amino acids are lost and replaced with 2 incorrect amino acids (Stenson et al., 2014; other references); Not observed at a significant frequency in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 22704718, 27638593, 21824559) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

3.1

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

Splicing

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over