rs199529046
Variant summary
Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM1PP3_StrongPP5_Very_Strong
The NM_004183.4(BEST1):c.602T>C(p.Ile201Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000148 in 1,613,940 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).
Frequency
Consequence
NM_004183.4 missense
Scores
Clinical Significance
Conservation
Genome browser will be placed here
ACMG classification
Verdict is Pathogenic. Variant got 14 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000658 AC: 10AN: 152048Hom.: 0 Cov.: 31
GnomAD3 exomes AF: 0.0000676 AC: 17AN: 251360Hom.: 0 AF XY: 0.0000589 AC XY: 8AN XY: 135864
GnomAD4 exome AF: 0.000157 AC: 229AN: 1461892Hom.: 0 Cov.: 39 AF XY: 0.000153 AC XY: 111AN XY: 727246
GnomAD4 genome AF: 0.0000658 AC: 10AN: 152048Hom.: 0 Cov.: 31 AF XY: 0.0000943 AC XY: 7AN XY: 74254
ClinVar
Submissions by phenotype
not provided Pathogenic:3Other:1
Published functional studies suggest this variant results in partial loss of function, however additional studies are needed to validate the functional effect of this variant in vivo (PMID: 29063836); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 22422030, 10798642, 26333019, 17110374, 21273940, 22183385, 30609409, 31455904, 32239196, 33154968, 33039401, 35806438, 34996991, 32036094, 29063836) -
- -
- -
This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 201 of the BEST1 protein (p.Ile201Thr). This variant is present in population databases (rs199529046, gnomAD 0.01%). This missense change has been observed in individual(s) with autosomal recessive bestrophinopathy (PMID: 22422030, 26333019). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. This variant has been reported in individual(s) with sporadic or autosomal dominant Best vitelliform macular dystrophy (PMID: 10798642, 21109774); however, the role of the variant in this condition is currently unclear. ClinVar contains an entry for this variant (Variation ID: 99726). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt BEST1 protein function with a positive predictive value of 95%. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on BEST1 function (PMID: 17110374). For these reasons, this variant has been classified as Pathogenic. -
Autosomal recessive bestrophinopathy Pathogenic:3
The p.Ile201Thr variant in BEST1 has been reported in the compound heterozygous state in 4 individuals (3 family members and 1 unrelated individual). The 4 pati ents were affected with autosomal recessive bestrophinopathy. None of 3 heterozy gous family members were affected (Zhao 2012; Wivestad Jansson 2016 ). This var iant was also reported in the heterozygous state, in one patient with autosomal dominant Best macular dystrophy; however, insufficient data was present to suppo rt a dominant role or carrier phenotype (Lotery 2000). The p.Ile201Thr variant h as been identified in 7/121,390 of chromosomes by the Exome Aggregation Consorti um (ExAC, http://exac.broadinstitute.org; dbSNP rs199529046), a frequency low en ough to be consistent with a recessive carrier frequency. Computational analyses suggest that the p.Ile201Thr variant may impact the protein. In summary, additi onal data is needed to confirm the clinical significance of this variant; howeve r based upon the published data, we would classify this variant as likely pathog enic for autosomal recessive bestrophinopathy. -
This sequence change is predicted to replace isoleucine with threonine at codon 201 of the BEST1 protein (p.Ile201Thr). The isoleucine residue is highly conserved (100 vertebrates, UCSC), and is located in the bestrophin (RFP-TM) chloride channel domain. There is a moderate physicochemical difference between isoleucine and threonine. The variant is present in a large population cohort at a frequency of 0.007%, which is consistent with recessive disease (rs199529046, 19/282,720 alleles, 0 homozygotes in gnomAD v2.1 - PM2). The variant has been identified in the homozygous state (with a less severe phenotype) and compound heterozygote with a second pathogenic allele in multiple cases with autosomal recessive bestrophinopathy, and segregates with disease in at least one family (PMID: 21273940, 22422030, 27764019, 29063836 - PM3_Strong, PP1_Moderate). The variant causes reduced calcium-activated chloride channel function in in vitro functional assays (PMID: 17110374, 29063836 - PS3_Supporting). Multiple lines of computational evidence predict a deleterious effect for the missense substitution (7/7 algorithms - PP3). Based on the classification scheme RMH ACMG Guidelines v1.2.1, this variant is classified as PATHOGENIC. Following criteria are met: PM3_Strong, PM2, PP1_Moderate, PS3_Supporting, PP3. -
Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Dominant negative and loss of function are known mechanisms of disease in this gene. Dominant negative variants are associated with autosomal dominant disease (macular dystrophy, vitelliform, 2, MIM#153700; vitreoretinochoroidopathy, MIM#193220) while loss of function variants are associated with autosomal recessive disease (bestrophinopathy, autosomal recessive, MIM#611809; PMID: 29668979). (I) 0108 - This gene is associated with both recessive and dominant disease (OMIM). (I) 0112 - The condition associated with this gene has incomplete penetrance. This has been observed in individuals with dominant vitelliform macular dystrophy (PMID: 21273940). (I) 0200 - Variant is predicted to result in a missense amino acid change from isoleucine to threonine. (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 (19 heterozygotes, 0 homozygotes). (SP) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (v2) (1 heterozygote, 0 homozygotes). (I) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0600 - Variant is located in the annotated bestrophin domain (DECIPHER). (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported multiple times as likely pathogenic and pathogenic, and has been observed in several compound heterozygous families with recessive vitelliform macular dystrophy (ClinVar, PMID: 22422030, PMID: 21273940). (SP) 0902 - This variant has moderate evidence for segregation with disease, where this variant was observed in three compound heterozygous siblings (PMID: 22422030). (SP) 1102 - Strong phenotype match for this individual. (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
Vitelliform macular dystrophy 2 Pathogenic:1
The BEST1 c.602T>C variant was identified in an individual with retinitis pigmentosa with a presumed dominant inheritance pattern. Through a review of available evidence we were able to apply the following criteria: PM2, PP3, PM3, PP1, PS3. Based on this evidence we have classified this variant as Pathogenic. -
BEST1-related disorder Pathogenic:1
The BEST1 c.602T>C (p.Ile201Thr) missense variant, also referred to as c.422T>C (p.Ile141Thr), has been reported in four studies in which it is found in a total of eight individuals from six unrelated families (Lotery et al. 2000; Kinnick et al. 2011; Zhao et al. 2012; Wivestad Jansson et al. 2016). Seven of the individuals are compound heterozygotes for the p.Ile201Thr variant, including three unrelated individuals with vitelliform macular dystrophy, three siblings with Best vitelliform macular dystrophy, and one individual with recessive bestrophinopathy. Another patient with Best vitelliform macular dystrophy was heterozygous for the p.Ile201Thr variant. The variant was also detected in a heterozygous state in four unaffected family members. The p.Ile201Thr variant has not been reported in the literature in patients with autosomal recessive retinitis pigmentosa or vitreoretinochoroidopathy. The p.Ile201Thr variant was absent from over 1500 control chromosomes but is reported at a frequency of 0.00010 in the European (non-Finnish) population of the Exome Aggregation Consortium. Comparative protein modeling by Guziewicz et al. (2012) suggests that the p.Ile201Thr variant could induce conformational rearrangements and alter inter-residue interactions. Based on the collective evidence, the p.Ile201Thr variant is classified as likely pathogenic for BEST1-related disorders. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at