X-153867795-C-T

Variant names:

• chrX-153867795-C-T
• rs879253716
• NM_001278116.2:c.1939+5G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_001278116.2(L1CAM):​c.1939+5G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: L1CAM NM_001278116.2 splice_region, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 1.06

Genes affected

L1CAM (HGNC:6470): (L1 cell adhesion molecule) The protein encoded by this gene is an axonal glycoprotein belonging to the immunoglobulin supergene family. The ectodomain, consisting of several immunoglobulin-like domains and fibronectin-like repeats (type III), is linked via a single transmembrane sequence to a conserved cytoplasmic domain. This cell adhesion molecule plays an important role in nervous system development, including neuronal migration and differentiation. Mutations in the gene cause X-linked neurological syndromes known as CRASH (corpus callosum hypoplasia, retardation, aphasia, spastic paraplegia and hydrocephalus). Alternative splicing of this gene results in multiple transcript variants, some of which include an alternate exon that is considered to be specific to neurons. [provided by RefSeq, May 2013]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant X-153867795-C-T is Pathogenic according to our data. Variant chrX-153867795-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 9999.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
L1CAM	NM_001278116.2	c.1939+5G>A		splice_region_variant, intron_variant	Intron 16 of 28	ENST00000370060.7	NP_001265045.1
L1CAM	NM_000425.5	c.1939+5G>A		splice_region_variant, intron_variant	Intron 15 of 27		NP_000416.1
L1CAM	NM_024003.3	c.1939+5G>A		splice_region_variant, intron_variant	Intron 15 of 26		NP_076493.1
L1CAM	NM_001143963.2	c.1924+5G>A		splice_region_variant, intron_variant	Intron 14 of 25		NP_001137435.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
L1CAM	ENST00000370060.7	c.1939+5G>A		splice_region_variant, intron_variant	Intron 16 of 28	5	NM_001278116.2	ENSP00000359077.1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 23

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Spastic paraplegia Pathogenic:1

Feb 14, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 15 of the L1CAM gene. It does not directly change the encoded amino acid sequence of the L1CAM protein. It affects a nucleotide within the consensus splice site. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with X-linked hydrocephalus (PMID: 15148591). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 9999). 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 may disrupt the consensus splice site. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

X-linked hydrocephalus syndrome Pathogenic:1

Jan 01, 2004

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.34
CADD	Benign	15
DANN	Benign	0.94

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.92		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.92		Position offset: 5

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs879253716; hg19: chrX-153133250;