rs199761611
Variant summary
Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate
The NM_030973.4(MED25):c.1966C>A(p.Pro656Thr) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000131 in 1,611,932 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 predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P656L) has been classified as Uncertain significance.
Frequency
Consequence
NM_030973.4 missense, splice_region
Scores
Clinical Significance
Conservation
Publications
- congenital cataract-microcephaly-nevus flammeus simplex-severe intellectual disability syndromeInheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, G2P, Labcorp Genetics (formerly Invitae)
- autosomal recessive non-syndromic intellectual disabilityInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- Charcot-Marie-Tooth disease type 2B2Inheritance: AR Classification: SUPPORTIVE, NO_KNOWN Submitted by: Orphanet, ClinGen
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ACMG classification
Our verdict: Likely_benign. The variant received -2 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| MED25 | NM_030973.4 | c.1966C>A | p.Pro656Thr | missense_variant, splice_region_variant | Exon 17 of 18 | ENST00000312865.10 | NP_112235.2 | |
| MED25 | NM_001378355.1 | c.1966C>A | p.Pro656Thr | missense_variant, splice_region_variant | Exon 17 of 18 | NP_001365284.1 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000138 AC: 21AN: 152208Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000946 AC: 23AN: 243146 AF XY: 0.000120 show subpopulations
GnomAD4 exome AF: 0.000130 AC: 190AN: 1459724Hom.: 0 Cov.: 32 AF XY: 0.000138 AC XY: 100AN XY: 726138 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.000138 AC: 21AN: 152208Hom.: 0 Cov.: 32 AF XY: 0.000108 AC XY: 8AN XY: 74360 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Charcot-Marie-Tooth disease type 2 Uncertain:2
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This sequence change replaces proline, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 656 of the MED25 protein (p.Pro656Thr). This variant is present in population databases (rs199761611, gnomAD 0.02%). This missense change has been observed in individual(s) with Charcot-Marie-Tooth disease (PMID: 26257172, 30039206). ClinVar contains an entry for this variant (Variation ID: 329887). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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. -
Tip-toe gait Pathogenic:1
In the molecular genetic analysis, the variant c.1966C>A p. (Pro656Thr) can be detected. The amino acid substitution is in a region responsible for binding of the retinoic acid receptor. The variant has been mentioned in the literature in connection with Charcot-Marie-Tooth disease [Gonzaga-Jauregui (2015) Cell Rep 12: 1169]. The authors describe a patient in whom the above variant in combination with a second heterozygous MED25 variant (c.1004C>T p.(Ala335Val)) was detected. However, the rating was the second variant Ala335Val was later withdrawn by the authors as a "causal pathogen" in another family with frequent occurrence of CMT [Leal (2018) Neurogenetics 19: 215]. Hereditary motor sensory neuropathy (HMSN), also known as Charcot-Marie-Tooth Disease (CMT), is the most commonly inherited peripheral polyneuropathy. It constitutes a group of inherited, progressive, motor and sensory peripheral nerve disorders with properties of demyelination, axonal degeneration, or both. It is classified by clinical characteristics, modes of inheritance, electrophysiologic features, metabolic defects, and specific gene markers. Our patients all walk on tiptoe, so they show similar symptoms. When we genetically test them with our toe walking panel, we find that around 90 per cent of them have a genetic variant that explains their toe walking. These can be assigned, for example, to the area of myopathies (such as variants of the COL6A3 gene), the area of hereditary neuropathies (such as variants of the KMT2C gene) or the area of metabolic diseases (such as variants of the PYGM gene). In a smaller group of patients with almost identical symptoms, no abnormality is found in the genes of our panel, but spastic paraplegia can be detected. In another small group of our toe walkers, no abnormalities can be detected in the genes analysed in our toe walking panel, nor do they suffer from spastic paraplegia, as is also the case with healthy children. In contrast to these, however, they show a tiptoe gait. These patients suffer from infantile cerebral palsy, in which toe walking can also be observed. -
Charcot-Marie-Tooth disease Uncertain:1
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not provided Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at