14-87982205-C-T

Position:

• chr14-87982205-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000153.4(GALC):​c.621G>A​(p.Lys207Lys) variant causes a splice region, synonymous change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000718 in 1,392,774 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 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)
  • Exomes 𝑓: 7.2e-7 (0 hom.)
• Consequence: GALC NM_000153.4 splice_region, synonymous
• Scores: Splicing: ADA: 0.9990
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:6
• Conservation: PhyloP100: 7.28

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GALC	NM_000153.4	c.621G>A	p.Lys207Lys	splice_region_variant, synonymous_variant	6/17	ENST00000261304.7	NP_000144.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GALC	ENST00000261304.7	c.621G>A	p.Lys207Lys	splice_region_variant, synonymous_variant	6/17	1	NM_000153.4	ENSP00000261304.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000405 AC: 1 AN: 246890 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 134118

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: 0.000167

GnomAD4 exome AF: 7.18e-7 AC: 1 AN: 1392774 Hom.: 0 Cov.: 24 AF XY: 0.00 AC XY: 0 AN XY: 696814

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.0000172

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:6

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Galactosylceramide beta-galactosidase deficiency Pathogenic:1 Uncertain:4

Pathogenic, criteria provided, single submitter	clinical testing	Pathology and Clinical Laboratory Medicine, King Fahad Medical City	-	Enzyme deficiency -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 29, 2023	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. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 550179). This variant has been observed in individual(s) with clinical features of Krabbe disease (PMID: 10833326, 26795590). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change affects codon 207 of the GALC mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the GALC protein. This variant also falls at the last nucleotide of exon 6, which is part of the consensus splice site for this exon. -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Dec 23, 2016	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center	Apr 04, 2024	- -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Aug 26, 2021	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Mar 07, 2019

Variant summary: GALC c.621G>A (p.Lys207Lys) 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: three predict the variant weakens a 5' donor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 243894 control chromosomes (gnomAD). c.621G>A has been reported in the literature in a homozygous individual affected with Krabbe Disease (Wenger_2000), and in a newborn screening sample indicative of low GALC enzyme activity, where the a second mutation was not provided (Orsini_2016). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. A ClinVar submission from a clinical diagnostic laboratory (evaluation after 2014) cites the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Feb 01, 2024

GALC: PM2, PP3, PP4 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.19
CADD	Benign	23
DANN	Benign	0.92

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.97		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs1428763453; hg19: chr14-88448549;