2-148469906-G-T

Variant names:

• chr2-148469906-G-T
• rs576930680
• NM_001378120.1:c.1963G>T

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001378120.1(MBD5):​c.1963G>T​(p.Ala655Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,640 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A655T) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MBD5 NM_001378120.1 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.22
• Publications: 0 publications found

Genes affected

MBD5 (HGNC:20444): (methyl-CpG binding domain protein 5) This gene encodes a member of the methyl-CpG-binding domain (MBD) family. The MBD consists of about 70 residues and is the minimal region required for a methyl-CpG-binding protein binding specifically to methylated DNA. In addition to the MBD domain, this protein contains a PWWP domain (Pro-Trp-Trp-Pro motif), which consists of 100-150 amino acids and is found in numerous proteins that are involved in cell division, growth and differentiation. Mutations in this gene cause an autosomal dominant type of cognitive disability. The encoded protein interacts with the polycomb repressive complex PR-DUB which catalyzes the deubiquitination of a lysine residue of histone 2A. Haploinsufficiency of this gene is associated with a syndrome involving microcephaly, intellectual disabilities, severe speech impairment, and seizures. Alternatively spliced transcript variants have been found, but their full-length nature is not determined. [provided by RefSeq, Jul 2017]

MBD5 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• intellectual disability, autosomal dominant 1

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• autosomal dominant non-syndromic intellectual disability

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.03274536).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MBD5	NM_001378120.1	c.1963G>T	p.Ala655Ser	missense_variant	Exon 8 of 14	ENST00000642680.2	NP_001365049.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MBD5	ENST00000642680.2	c.1963G>T	p.Ala655Ser	missense_variant	Exon 8 of 14		NM_001378120.1	ENSP00000493871.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461640 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 727130

African (AFR) AF: 0.00 AC: 0 AN: 33456

American (AMR) AF: 0.00 AC: 0 AN: 44702

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

East Asian (EAS) AF: 0.00 AC: 0 AN: 39688

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53394

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111878

Other (OTH) AF: 0.00 AC: 0 AN: 60376

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal dominant 1 Uncertain:1

Aug 04, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MBD5 protein function. ClinVar contains an entry for this variant (Variation ID: 2198788). This variant has not been reported in the literature in individuals affected with MBD5-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 655 of the MBD5 protein (p.Ala655Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.057
BayesDel_addAF	Benign	-0.24	T
BayesDel_noAF	Benign	-0.59
CADD	Benign	18
DANN	Benign	0.27
DEOGEN2	Benign	0.038	T;.;.;.;T
Eigen	Benign	-0.70
Eigen_PC	Benign	-0.45
FATHMM_MKL	Benign	0.53	D
LIST_S2	Benign	0.54	T;.;T;T;T
M_CAP	Benign	0.0030	T
MetaRNN	Benign	0.033	T;T;T;T;T
MetaSVM	Benign	-0.98	T
MutationAssessor	Benign	-0.69	N;.;.;N;.
PhyloP100		2.2
PrimateAI	Uncertain	0.55	T
PROVEAN	Benign	-0.070	N;.;.;.;N
REVEL	Benign	0.075
Sift	Benign	1.0	T;.;.;.;T
Sift4G	Benign	1.0	T;.;.;T;T
Polyphen		0.0	B;.;.;B;.
Vest4		0.21
MutPred		0.23		Gain of phosphorylation at A655 (P = 0.0197);Gain of phosphorylation at A655 (P = 0.0197);Gain of phosphorylation at A655 (P = 0.0197);Gain of phosphorylation at A655 (P = 0.0197);Gain of phosphorylation at A655 (P = 0.0197);
MVP		0.13
MPC		0.14
ClinPred		0.087	T
GERP RS		5.0
Varity_R		0.022
gMVP		0.25
Mutation Taster		=99/1	polymorphism

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

Other links and lift over

dbSNP: rs576930680; hg19: chr2-149227475;