rs370905417

Positions:

• chr11-62705346-T-A
• chr11-62705346-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_001122955.4(BSCL2):​c.359A>T​(p.Tyr120Phe) variant causes a missense change. The variant allele was found at a frequency of 0.0000164 in 1,461,686 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: BSCL2 NM_001122955.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 6.96

Genes affected

BSCL2 (HGNC:15832): (BSCL2 lipid droplet biogenesis associated, seipin) This gene encodes the multi-pass transmembrane protein protein seipin. This protein localizes to the endoplasmic reticulum and may be important for lipid droplet morphology. Mutations in this gene have been associated with congenital generalized lipodystrophy type 2 or Berardinelli-Seip syndrome, a rare autosomal recessive disease characterized by a near absence of adipose tissue and severe insulin resistance. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. Naturally occurring read-through transcription occurs between this locus and the neighboring locus HNRNPUL2 (heterogeneous nuclear ribonucleoprotein U-like 2).[provided by RefSeq, Mar 2011]

HNRNPUL2-BSCL2 (HGNC:49189): (HNRNPUL2-BSCL2 readthrough (NMD candidate)) This locus represents naturally occurring read-through transcription between the neighboring HNRNPUL2 (heterogeneous nuclear ribonucleoprotein U-like 2) and BSCL2 (Berardinelli-Seip congenital lipodystrophy 2 (seipin)) genes on chromosome 11. The read-through transcript is a candidate for nonsense-mediated mRNA decay (NMD), and is unlikely to produce a protein product. [provided by RefSeq, Mar 2011]

BSCL2 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a topological_domain Lumenal (size 194) in uniprot entity BSCL2_HUMAN there are 12 pathogenic changes around while only 0 benign (100%) in NM_001122955.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.97

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BSCL2	NM_001122955.4	c.359A>T	p.Tyr120Phe	missense_variant	2/11	ENST00000360796.10	NP_001116427.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BSCL2	ENST00000360796.10	c.359A>T	p.Tyr120Phe	missense_variant	2/11	1	NM_001122955.4	ENSP00000354032.5
HNRNPUL2-BSCL2	ENST00000403734.2	n.*410A>T		non_coding_transcript_exon_variant	15/24	2		ENSP00000456010.1
HNRNPUL2-BSCL2	ENST00000403734.2	n.*410A>T		3_prime_UTR_variant	15/24	2		ENSP00000456010.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250532 Hom.: 0 AF XY: 0.00000738 AC XY: 1 AN XY: 135502

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000884

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000164 AC: 24 AN: 1461686 Hom.: 0 Cov.: 31 AF XY: 0.0000165 AC XY: 12 AN XY: 727128

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000207

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 22, 2020

The p.Y56F variant (also known as c.167A>T), located in coding exon 1 of the BSCL2 gene, results from an A to T substitution at nucleotide position 167. The tyrosine at codon 56 is replaced by phenylalanine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Charcot-Marie-Tooth disease type 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 06, 2022

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. 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 C15"). ClinVar contains an entry for this variant (Variation ID: 1344241). This variant has not been reported in the literature in individuals affected with BSCL2-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.0009%). This sequence change replaces tyrosine, which is neutral and polar, with phenylalanine, which is neutral and non-polar, at codon 56 of the BSCL2 protein (p.Tyr56Phe). -

Hereditary spastic paraplegia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Genome Diagnostics Laboratory, The Hospital for Sick Children

Nov 15, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.81	.;.;.;D;D;D;.;D;D;.
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.96	D;D;D;.;.;D;D;D;D;D
M_CAP	Uncertain	0.10	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.50	D
MutationAssessor	Benign	1.9	.;L;.;L;L;L;.;.;.;.
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-3.3	D;D;D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.75
Sift	Benign	0.15	T;T;T;D;D;D;T;D;T;T
Sift4G	Benign	0.11	T;T;T;T;T;T;.;.;.;D
Polyphen		0.99, 1.0	.;D;.;D;D;D;.;.;.;.
Vest4		0.63
MutPred		0.93		.;Loss of catalytic residue at Y56 (P = 0.0686);.;Loss of catalytic residue at Y56 (P = 0.0686);Loss of catalytic residue at Y56 (P = 0.0686);Loss of catalytic residue at Y56 (P = 0.0686);Loss of catalytic residue at Y56 (P = 0.0686);.;Loss of catalytic residue at Y56 (P = 0.0686);.;
MVP		0.85
ClinPred		0.93	D
GERP RS		5.6
Varity_R		0.42
gMVP		0.59

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs370905417; hg19: chr11-62472818;