NM_001278116.2:c.807-6G>A

Variant names:

• chrX-153870246-C-T
• rs886039405
• NM_001278116.2:c.807-6G>A

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM2 PP3 PP5_Very_Strong

The NM_001278116.2(L1CAM):​c.807-6G>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 0.000000913 in 1,095,836 control chromosomes in the GnomAD database, with no homozygous occurrence. There are no hemizygote samples in GnomAD. 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: 24)
  • Exomes 𝑓: 9.1e-7 (0 hom. 0 hem.)
• Consequence: L1CAM NM_001278116.2 splice_region, intron
• Scores: Splicing: ADA: 0.9995
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 1.85
• Publications: 0 publications found

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]

L1CAM Gene-Disease associations (from GenCC):

• L1 syndrome

  Inheritance: XL Classification: DEFINITIVE Submitted by: ClinGen
• X-linked hydrocephalus with stenosis of the aqueduct of Sylvius

  Inheritance: XL Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Genomics England PanelApp
• MASA syndrome

  Inheritance: XL Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet
• X-linked complicated corpus callosum dysgenesis

  Inheritance: XL Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• X-linked complicated spastic paraplegia type 1

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant X-153870246-C-T is Pathogenic according to our data. Variant chrX-153870246-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 265221.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001278116.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	L1CAM	NM_001278116.2	MANE Select	c.807-6G>A		splice_region intron	N/A	NP_001265045.1	P32004-1
	L1CAM	NM_000425.5		c.807-6G>A		splice_region intron	N/A	NP_000416.1	P32004-1
	L1CAM	NM_024003.3		c.807-6G>A		splice_region intron	N/A	NP_076493.1	P32004-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	L1CAM	ENST00000370060.7	TSL:5 MANE Select	c.807-6G>A		splice_region intron	N/A	ENSP00000359077.1	P32004-1
	L1CAM	ENST00000361699.8	TSL:1	c.807-6G>A		splice_region intron	N/A	ENSP00000355380.4	P32004-2
	L1CAM	ENST00000361981.7	TSL:1	c.792-6G>A		splice_region intron	N/A	ENSP00000354712.3	P32004-3

Frequencies

GnomAD3 genomes Cov.: 24

GnomAD4 exome AF: 9.13e-7 AC: 1 AN: 1095836 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 361354

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 26373

American (AMR) AF: 0.00 AC: 0 AN: 35178

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 19327

East Asian (EAS) AF: 0.00 AC: 0 AN: 30178

South Asian (SAS) AF: 0.00 AC: 0 AN: 53983

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 40216

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4059

European-Non Finnish (NFE) AF: 0.00000119 AC: 1 AN: 840535

Other (OTH) AF: 0.00 AC: 0 AN: 45987

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 24

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	-	-	not provided (2)
1	-	-	L1 syndrome (1)
1	-	-	Spastic paraplegia (1)
1	-	-	X-linked hydrocephalus syndrome (1)
1	-	-	X-linked hydrocephalus syndrome;C0795953:MASA syndrome;C1839909:X-linked complicated corpus callosum dysgenesis (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.72
CADD	Benign	22
DANN	Benign	0.52
PhyloP100		1.9
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		1.0		Position offset: -2
DS_AL_spliceai		0.39		Position offset: -6

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

Other links and lift over

dbSNP: rs886039405; hg19: chrX-153135701;