NM_018136.5:c.3741+1G>A

Variant names:

• chr1-197122158-C-T
• rs199422160
• NM_018136.5:c.3741+1G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_018136.5(ASPM):​c.3741+1G>A variant causes a splice donor, intron change. The variant allele was found at a frequency of 0.000000687 in 1,456,224 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: ASPM NM_018136.5 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1 O:1
• Conservation: PhyloP100: 5.57
• Publications: 5 publications found

Genes affected

ASPM (HGNC:19048): (assembly factor for spindle microtubules) This gene is the human ortholog of the Drosophila melanogaster 'abnormal spindle' gene (asp), which is essential for normal mitotic spindle function in embryonic neuroblasts. Studies in mouse also suggest a role of this gene in mitotic spindle regulation, with a preferential role in regulating neurogenesis. Mutations in this gene are associated with microcephaly primary type 5. Multiple transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, May 2011]

ASPM Gene-Disease associations (from GenCC):

• microcephaly 5, primary, autosomal recessive

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• autosomal recessive primary microcephaly

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-197122158-C-T is Pathogenic according to our data. Variant chr1-197122158-C-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 21581.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ASPM	NM_018136.5	c.3741+1G>A		splice_donor_variant, intron_variant	Intron 15 of 27	ENST00000367409.9	NP_060606.3
ASPM	NM_001206846.2	c.3741+1G>A		splice_donor_variant, intron_variant	Intron 15 of 26		NP_001193775.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ASPM	ENST00000367409.9	c.3741+1G>A		splice_donor_variant, intron_variant	Intron 15 of 27	1	NM_018136.5	ENSP00000356379.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000402 AC: 1 AN: 248626 AF XY: 0.00

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: 0.00000890

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1456224 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 724720

⚠️ 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: 33338

American (AMR) AF: 0.00 AC: 0 AN: 44528

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26054

East Asian (EAS) AF: 0.00 AC: 0 AN: 39618

South Asian (SAS) AF: 0.00 AC: 0 AN: 86058

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53294

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5730

European-Non Finnish (NFE) AF: 9.03e-7 AC: 1 AN: 1107422

Other (OTH) AF: 0.00 AC: 0 AN: 60182

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Jul 14, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 15 of the ASPM gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in ASPM are known to be pathogenic (PMID: 19028728, 23611254). This variant is present in population databases (rs199422160, gnomAD 0.0009%). Disruption of this splice site has been observed in individual(s) with autosomal recessive primary microcephaly (PMID: 19028728, 20978018). ClinVar contains an entry for this variant (Variation ID: 21581). 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. -

Microcephaly 5, primary, autosomal recessive Other:1

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	32
DANN	Uncertain	0.99
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Uncertain	0.95	D
PhyloP100		5.6
GERP RS		5.7
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: 1

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

Other links and lift over

dbSNP: rs199422160; hg19: chr1-197091288;