rs121908253
Variant summary
Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2PP5BP4BS1_Supporting
The NM_133459.4(CCBE1):c.472C>T(p.Arg158Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000213 in 1,613,426 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 Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_133459.4 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Uncertain_significance. Variant got 1 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000217 AC: 33AN: 152140Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.000207 AC: 52AN: 251206Hom.: 0 AF XY: 0.000184 AC XY: 25AN XY: 135758
GnomAD4 exome AF: 0.000213 AC: 311AN: 1461168Hom.: 0 Cov.: 30 AF XY: 0.000213 AC XY: 155AN XY: 726924
GnomAD4 genome AF: 0.000217 AC: 33AN: 152258Hom.: 0 Cov.: 33 AF XY: 0.000228 AC XY: 17AN XY: 74434
ClinVar
Submissions by phenotype
Hennekam lymphangiectasia-lymphedema syndrome 1 Pathogenic:4Uncertain:1Other:1
Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Likely Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with Hennekam lymphangiectasia-lymphedema syndrome 1, (MIM#235510). (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to cysteine. (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 for a recessive condition (58 heterozygotes, 0 homozygotes). (SP) 0309 - Multiple alternative amino acid changes at the same position have been observed in gnomAD (v2) (highest allele count: 24 heterozygotes, 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 calcium-binding EGF domain (DECIPHER). (I) 0710 - Another missense variant comparable to the one identified in this case has inconclusive previous evidence for pathogenicity. This alternative change, p.(Arg158His), has been reported as a VUS (ClinVar). (I) 0802 - This variant has moderate previous evidence of pathogenicity in unrelated individuals. This variant has been reported as a VUS, likely pathogenic and pathogenic (ClinVar, LOVD). It has also been observed in two compound heterozygous individuals with Hennekam syndrome or lymphangiectasia and lymphoedema, and a homozygous individual with intestinal lymphangiectasia (PMID: 19935664, PMID: 32472549, PMID: 32629717). (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1010 - Functional evidence for this variant is inconclusive. Rescue attempts of zebrafish knockdown demonstrated partial rescue, and this variant did not affect VEGFC signalling both in vitro and in vivo (PMID: 19935664, PMID: 25814692). (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
The variant is observed at an extremely low frequency in the gnomAD v4.1.0 dataset (total allele frequency: 0.021%).In silico tool predictions suggest damaging effect of the variant on gene or gene product [REVEL: 0.75 (>=0.6, sensitivity 0.68 and specificity 0.92)]. -
PM2_Supporting+PP3+PM3_Strong+PP4 -
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not provided Pathogenic:4Uncertain:1
Published functional studies demonstrate activity comparable to wildtype and that the variant does not affect the ability of the protein to activate VEGFC processing (PMID: 19935664, 25814692); 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: 26686525, 25925991, 33507128, 32472549, 19935664, 34426522, 32629717, 25814692) -
This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 158 of the CCBE1 protein (p.Arg158Cys). This variant is present in population databases (rs121908253, gnomAD 0.04%). This missense change has been observed in individual(s) with Hennekam lymphangiectasia-lymphedema syndrome (PMID: 19935664, 32472549, 32629717). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 449). 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 not expected to disrupt CCBE1 protein function with a negative predictive value of 80%. Experimental studies have shown that this missense change does not substantially affect CCBE1 function (PMID: 25814692). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -
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not specified Uncertain:1
Variant summary: CCBE1 c.472C>T (p.Arg158Cys) results in a non-conservative amino acid change located in the EGF-like domain (IPR000742) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00021 in 251206 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in CCBE1 causing Hennekam Lymphangiectasia-Lymphedema Syndrome (0.00021 vs 0.00056), allowing no conclusion about variant significance. c.472C>T has been reported in the literature in individuals affected with Hennekam Lymphangiectasia-Lymphedema Syndrome (examples: Alders_2009, Ren_2020 and Fattorusso_2020). These data indicate that the variant may be associated with disease. Multiple publications report experimental evidence evaluating an impact on protein function. These results showed conflcting effects on protein function (example: Alders_2009 and Roukens_2015). Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as likely pathogenic, and as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -
CCBE1-related disorder Uncertain:1
The CCBE1 c.472C>T variant is predicted to result in the amino acid substitution p.Arg158Cys. This variant was reported in the compound heterozygous state along with a premature termination variant in a patient with lymphatic dysplasia (Alders et al 2009. PubMed ID: 19935664). This variant was also reported in the homozygous state in a patient with intestinal lymphangiectasia, edema of the lower extremities and facial dysmorphisms (Fattorusso et al 2020. PubMed ID: 32629717). This variant is reported in 0.036% of alleles in individuals of European (Finnish) descent in gnomAD (http://gnomad.broadinstitute.org/variant/18-57134052-G-A). Although we suspect that this variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at