chr19-2438370-C-T

Variant names:

• chr19-2438370-C-T
• rs747264492
• NM_032737.4:c.558+5G>A

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_032737.4(LMNB2):​c.558+5G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,460,750 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: LMNB2 NM_032737.4 splice_region, intron
• Scores: Splicing: ADA: 0.4767
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.21
• Publications: 0 publications found

Genes affected

LMNB2 (HGNC:6638): (lamin B2) This gene encodes a B type nuclear lamin. The nuclear lamina consists of a two-dimensional matrix of proteins located next to the inner nuclear membrane. The lamin family of proteins make up the matrix and are highly conserved in evolution. During mitosis, the lamina matrix is reversibly disassembled as the lamin proteins are phosphorylated. Lamin proteins are thought to be involved in nuclear stability, chromatin structure and gene expression. Vertebrate lamins consist of two types, A and B. Mutations in this gene are associated with acquired partial lipodystrophy. [provided by RefSeq, May 2012]

LMNB2 Gene-Disease associations (from GenCC):

• microcephaly 27, primary, autosomal dominant

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• progressive myoclonic epilepsy type 9

  Inheritance: AR Classification: STRONG, SUPPORTIVE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
• microcephaly

  Inheritance: AD Classification: MODERATE Submitted by: Franklin by Genoox
• lipodystrophy, partial, acquired, susceptibility to

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• central nervous system malformation

  Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Likely_benign. The variant received -4 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.74).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LMNB2	NM_032737.4	c.558+5G>A		splice_region_variant, intron_variant	Intron 3 of 11	ENST00000325327.4	NP_116126.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
LMNB2	ENST00000325327.4	c.558+5G>A		splice_region_variant, intron_variant	Intron 3 of 11	1	NM_032737.4	ENSP00000327054.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000200 AC: 5 AN: 249730 AF XY: 0.0000148

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1460750 Hom.: 0 Cov.: 33 AF XY: 0.00000550 AC XY: 4 AN XY: 726672

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.0000696 AC: 6 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52436

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111894

Other (OTH) AF: 0.0000166 AC: 1 AN: 60368

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Lipodystrophy, partial, acquired, susceptibility to;C4225289:Progressive myoclonic epilepsy type 9 Uncertain:1

Jun 13, 2022

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. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. ClinVar contains an entry for this variant (Variation ID: 475785). This variant has not been reported in the literature in individuals affected with LMNB2-related conditions. This variant is present in population databases (rs747264492, gnomAD 0.01%). This sequence change falls in intron 3 of the LMNB2 gene. It does not directly change the encoded amino acid sequence of the LMNB2 protein. It affects a nucleotide within the consensus splice site. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.74
CADD	Benign	18
DANN	Benign	0.76
PhyloP100		3.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.3

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.48
dbscSNV1_RF	Benign	0.51
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: rs747264492; hg19: chr19-2438368;