16-75473660-G-A

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BS1_Supporting

The NM_021615.5(CHST6):c.*4981C>T variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00042 in 152,204 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.00042 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CHST6 NM_021615.5 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.259

Genes affected

CHST6 (HGNC:6938): (carbohydrate sulfotransferase 6) The protein encoded by this gene is an enzyme that catalyzes the transfer of a sulfate group to the GlcNAc residues of keratan. Keratan sulfate helps maintain corneal transparency. Defects in this gene are a cause of macular corneal dystrophy (MCD). [provided by RefSeq, Jan 2010]

ACMG classification

Verdict is Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.96).
• BS1: Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.00042 (64/152204) while in subpopulation NFE AF= 0.000853 (58/68014). AF 95% confidence interval is 0.000677. There are 0 homozygotes in gnomad4. There are 31 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CHST6	NM_021615.5	c.*4981C>T		3_prime_UTR_variant	3/3	ENST00000332272.9
CHST6	NR_163480.1	n.734-193C>T		intron_variant, non_coding_transcript_variant
CHST6	NR_163481.1	n.578-193C>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CHST6	ENST00000332272.9	c.*4981C>T		3_prime_UTR_variant	3/3	3	NM_021615.5	P1
CHST6	ENST00000649341.1	c.*109-193C>T		intron_variant, NMD_transcript_variant
CHST6	ENST00000649824.1	c.*558-152C>T		intron_variant, NMD_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.000414 AC: 63 AN: 152086 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000121

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: 0.000838

Gnomad OTH AF: 0.000479

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 6 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 4

Gnomad4 NFE exome AF: 0.00

GnomAD4 genome AF: 0.000420 AC: 64 AN: 152204 Hom.: 0 Cov.: 32 AF XY: 0.000417 AC XY: 31 AN XY: 74408

Gnomad4 AFR AF: 0.000120

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000853

Gnomad4 OTH AF: 0.000474

Alfa AF: 0.000794 Hom.: 0

Bravo AF: 0.000412

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Macular corneal dystrophy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.96
Cadd	Benign	1.1
Dann	Benign	0.44

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

Publications

LitVar

Other links and lift over

dbSNP: rs532430246; hg19: chr16-75507558;