11-2885055-CGCCGGG-CGCCGGGGCCGGG

Variant names:

• chr11-2885055-C-CGCCGGG
• rs1201148541
• NM_001122630.2:c.396_401dupCCCGGC

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001122630.2(CDKN1C):​c.396_401dupCCCGGC​(p.Ala134_Ser135insProAla) variant causes a disruptive inframe insertion change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000168 in 1,193,552 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. A134A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000017 (0 hom.)
• Consequence: CDKN1C NM_001122630.2 disruptive_inframe_insertion
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.317
• Publications: 0 publications found

Genes affected

CDKN1C (HGNC:1786): (cyclin dependent kinase inhibitor 1C) This gene is imprinted, with preferential expression of the maternal allele. The encoded protein is a tight-binding, strong inhibitor of several G1 cyclin/Cdk complexes and a negative regulator of cell proliferation. Mutations in this gene are implicated in sporadic cancers and Beckwith-Wiedemann syndorome, suggesting that this gene is a tumor suppressor candidate. Three transcript variants encoding two different isoforms have been found for this gene. [provided by RefSeq, Oct 2010]

CDKN1C Gene-Disease associations (from GenCC):

• Beckwith-Wiedemann syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• IMAGe syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Illumina, G2P, Ambry Genetics
• rhabdomyosarcoma

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• Beckwith-Wiedemann syndrome due to CDKN1C mutation

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• intrauterine growth restriction-short stature-early adult-onset diabetes syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Silver-Russell syndrome

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN1C	NM_001122630.2	c.396_401dupCCCGGC	p.Ala134_Ser135insProAla	disruptive_inframe_insertion	Exon 2 of 4	ENST00000440480.8	NP_001116102.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CDKN1C	ENST00000440480.8	c.396_401dupCCCGGC	p.Ala134_Ser135insProAla	disruptive_inframe_insertion	Exon 2 of 4	1	NM_001122630.2	ENSP00000411257.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00 AC: 0 AN: 5034 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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000168 AC: 2 AN: 1193552 Hom.: 0 Cov.: 30 AF XY: 0.00000173 AC XY: 1 AN XY: 577442

⚠️ 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: 23148

American (AMR) AF: 0.00 AC: 0 AN: 9498

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 16166

East Asian (EAS) AF: 0.0000364 AC: 1 AN: 27464

South Asian (SAS) AF: 0.0000204 AC: 1 AN: 49098

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 28526

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 3328

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 987336

Other (OTH) AF: 0.00 AC: 0 AN: 48988

⚠️ 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.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Beckwith-Wiedemann syndrome Uncertain:1

May 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant, c.429_434dup, results in the insertion of 2 amino acid(s) of the CDKN1C protein (p.Pro144_Ala145dup), but otherwise preserves the integrity of the reading frame. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CDKN1C-related conditions. ClinVar contains an entry for this variant (Variation ID: 524685). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.32

Splicing

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

Other links and lift over

dbSNP: rs1201148541; hg19: chr11-2906285;