11-61959892-G-T

Position:

• chr11-61959892-G-T

Variant summary

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

The NM_001363593.2(BEST1):​c.-24G>T variant causes a 5 prime UTR premature start codon gain change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: BEST1 NM_001363593.2 5_prime_UTR_premature_start_codon_gain
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.04

Genes affected

BEST1 (HGNC:12703): (bestrophin 1) This gene encodes a member of the bestrophin gene family. This small gene family is characterized by proteins with a highly conserved N-terminus with four to six transmembrane domains. Bestrophins may form chloride ion channels or may regulate voltage-gated L-type calcium-ion channels. Bestrophins are generally believed to form calcium-activated chloride-ion channels in epithelial cells but they have also been shown to be highly permeable to bicarbonate ion transport in retinal tissue. Mutations in this gene are responsible for juvenile-onset vitelliform macular dystrophy (VMD2), also known as Best macular dystrophy, in addition to adult-onset vitelliform macular dystrophy (AVMD) and other retinopathies. Alternative splicing results in multiple variants encoding distinct isoforms.[provided by RefSeq, Nov 2008]

FTH1 (HGNC:3976): (ferritin heavy chain 1) This gene encodes the heavy subunit of ferritin, the major intracellular iron storage protein in prokaryotes and eukaryotes. It is composed of 24 subunits of the heavy and light ferritin chains. Variation in ferritin subunit composition may affect the rates of iron uptake and release in different tissues. A major function of ferritin is the storage of iron in a soluble and nontoxic state. Defects in ferritin proteins are associated with several neurodegenerative diseases. This gene has multiple pseudogenes. Several alternatively spliced transcript variants have been observed, but their biological validity has not been determined. [provided by RefSeq, Jul 2008]

BEST1 (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
BEST1	NM_004183.4	c.949G>T	p.Val317Leu	missense_variant, splice_region_variant	9/11	ENST00000378043.9	NP_004174.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BEST1	ENST00000378043.9	c.949G>T	p.Val317Leu	missense_variant, splice_region_variant	9/11	1	NM_004183.4	ENSP00000367282.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive bestrophinopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Molecular Genetics, Royal Melbourne Hospital

Apr 23, 2020

This sequence change is predicted to replace valine with leucine at codon 317 of the BEST1 protein (p.Val317Leu). The valine residue is moderately conserved (100 vertebrates, UCSC), and is located within the C-terminal cytoplasmic domain. There is a small physicochemical difference between valine and leucine. The variant is absent in a large population cohort (gnomAD v2.1 - PM2). This variant is not reported in the relevant medical literature or databases. Multiple lines of computational evidence predict a deleterious effect for the missense substitution (7/7 algorithms - PP3). A different missense change at this amino acid residue (p.Val317Met) determined to be pathogenic has been seen before (PMID: 18179881, 21330666 - PM5). Based on the classification scheme RMH ACMG Guidelines v1.2.1, this variant is classified as VARIANT of UNCERTAIN SIGNIFICANCE. Following criteria are met: PM2, PM5, PP3. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.33	T
M_CAP	Uncertain	0.20	D
MetaRNN	Uncertain	0.44	T
MetaSVM	Pathogenic	1.0	D
PROVEAN	Benign	-0.48	N
REVEL	Uncertain	0.43
Sift	Uncertain	0.013	D
Sift4G	Benign	0.27	T
Vest4		0.32
MutPred		0.17		Loss of catalytic residue at H50 (P = 0.1031);
MVP		0.96
ClinPred		0.99	D
GERP RS		4.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.10		Details are displayed if max score is > 0.2

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr11-61727364;