8-6455240-G-GAC

Variant names:

• chr8-6455240-G-GAC
• rs1554496609
• NM_024596.5:c.1924_1925insCA

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_024596.5(MCPH1):​c.1924_1925insCA​(p.Arg642ThrfsTer10) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MCPH1 NM_024596.5 frameshift
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 1.06
• Publications: 0 publications found

Genes affected

MCPH1 (HGNC:6954): (microcephalin 1) This gene encodes a DNA damage response protein. The encoded protein may play a role in G2/M checkpoint arrest via maintenance of inhibitory phosphorylation of cyclin-dependent kinase 1. Mutations in this gene have been associated with primary autosomal recessive microcephaly 1 and premature chromosome condensation syndrome. Alternatively spliced transcript variants have been described. [provided by RefSeq, Feb 2010]

MCPH1 Gene-Disease associations (from GenCC):

• microcephaly 1, primary, autosomal recessive

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• microcephaly with intellectual disability

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• autosomal recessive primary microcephaly

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• hereditary breast carcinoma

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• familial ovarian cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-6455240-G-GAC is Pathogenic according to our data. Variant chr8-6455240-G-GAC is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 435835.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MCPH1	NM_024596.5	c.1924_1925insCA	p.Arg642ThrfsTer10	frameshift_variant	Exon 9 of 14	ENST00000344683.10	NP_078872.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MCPH1	ENST00000344683.10	c.1924_1925insCA	p.Arg642ThrfsTer10	frameshift_variant	Exon 9 of 14	1	NM_024596.5	ENSP00000342924.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly 1, primary, autosomal recessive Pathogenic:1

Sep 05, 2019

Genetic Services Laboratory, University of Chicago

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Autosomal recessive primary microcephaly Pathogenic:1

Sep 04, 2019

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: MCPH1 c.1924_1925insCA (p.Arg642ThrfsX10) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant was absent in 249,466 control chromosomes (gnomAD). To our knowledge, no occurrence of c.1924_1925insCA in individuals affected with Primary autosomal recessive microcephaly and no experimental evidence demonstrating an impact on protein function have been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		1.1

Splicing

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

Other links and lift over

dbSNP: rs1554496609; hg19: chr8-6312761;