rs145199888

Positions:

• chr11-9856624-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_030962.4(SBF2):​c.2197C>G​(p.Gln733Glu) variant causes a missense change. The variant allele was found at a frequency of 0.000183 in 1,614,026 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:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00019 (0 hom.)
• Consequence: SBF2 NM_030962.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:6 B:1
• Conservation: PhyloP100: 6.74

Genes affected

SBF2 (HGNC:2135): (SET binding factor 2) This gene encodes a pseudophosphatase and member of the myotubularin-related protein family. This gene maps within the CMT4B2 candidate region of chromosome 11p15 and mutations in this gene have been associated with Charcot-Marie-Tooth Disease, type 4B2. [provided by RefSeq, Jul 2008]

(HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.18053326).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SBF2	NM_030962.4	c.2197C>G	p.Gln733Glu	missense_variant	19/40	ENST00000256190.13
LOC101928008	NR_120539.1	n.135+17348G>C		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SBF2	ENST00000256190.13	c.2197C>G	p.Gln733Glu	missense_variant	19/40	1	NM_030962.4	P3
	ENST00000533659.1	n.134+17348G>C		intron_variant, non_coding_transcript_variant		1

Frequencies

GnomAD3 genomes AF: 0.000138 AC: 21 AN: 152140 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000328

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000235

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000191 AC: 48 AN: 251444 Hom.: 0 AF XY: 0.000177 AC XY: 24 AN XY: 135890

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000116

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000361

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.000187 AC: 274 AN: 1461886 Hom.: 0 Cov.: 33 AF XY: 0.000169 AC XY: 123 AN XY: 727244

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.000112

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000233

Gnomad4 OTH exome AF: 0.000116

GnomAD4 genome AF: 0.000138 AC: 21 AN: 152140 Hom.: 0 Cov.: 32 AF XY: 0.000148 AC XY: 11 AN XY: 74326

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.000328

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000235

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000319 Hom.: 0

Bravo AF: 0.000140

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000233 AC: 2

ExAC AF: 0.000123 AC: 15

EpiCase AF: 0.000382

EpiControl AF: 0.000474

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:6 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Jun 03, 2019	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Jun 01, 2018	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Feb 28, 2018	- -

Charcot-Marie-Tooth disease type 4B2 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Uncertain significance, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Apr 26, 2019	The SBF2 c.2197C>G; p.Gln733Glu variant (rs145199888), to our knowledge, is not reported in the medical literature but is reported in ClinVar (Variation ID: 306600). This variant is listed in the Genome Aggregation Database (gnomAD) with an overall population frequency of 0.03 percent in the European Non-Finnish (identified on 45 out of 129,148 chromosomes). The glutamine at codon 733 is weakly conserved, and computational analyses (SIFT, PolyPhen-2) predict that this variant is tolerated. Due to limited information, the clinical significance of the p.Gln733Glu variant is uncertain at this time. -

Tip-toe gait Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Practice for Gait Abnormalities, David Pomarino, Competency Network Toe Walking c/o Practice Pomarino

Feb 10, 2021

We conducted a clinical examination of patients about toe walking. The SBF2 c.2197C>G was detected in 3 patients. We also examined a control group of children without toe walking (100 children). In this group this variant could not be identified. 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. -

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 25, 2021

The p.Q733E variant (also known as c.2197C>G), located in coding exon 19 of the SBF2 gene, results from a C to G substitution at nucleotide position 2197. The glutamine at codon 733 is replaced by glutamic acid, an amino acid with highly similar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Charcot-Marie-Tooth disease type 4 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 06, 2023

This sequence change replaces glutamine, which is neutral and polar, with glutamic acid, which is acidic and polar, at codon 733 of the SBF2 protein (p.Gln733Glu). This variant is present in population databases (rs145199888, gnomAD 0.03%). This variant has not been reported in the literature in individuals affected with SBF2-related conditions. ClinVar contains an entry for this variant (Variation ID: 306600). 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 SBF2 protein function with a negative predictive value of 80%. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.082
BayesDel_addAF	Benign	-0.33	T
BayesDel_noAF	Benign	-0.40
CADD	Benign	23
DANN	Uncertain	0.98
DEOGEN2	Benign	0.13	T
Eigen	Benign	0.012
Eigen_PC	Benign	0.20
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.90	D
M_CAP	Benign	0.016	T
MetaRNN	Benign	0.18	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Uncertain	2.2	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.57	T
PROVEAN	Benign	-1.6	N
REVEL	Benign	0.12
Sift	Benign	0.35	T
Sift4G	Benign	0.39	T
Polyphen		0.10	B
Vest4		0.43
MVP		0.55
MPC		0.21
ClinPred		0.077	T
GERP RS		5.3
Varity_R		0.14
gMVP		0.43

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

Publications

LitVar

Other links and lift over

dbSNP: rs145199888; hg19: chr11-9878171;