NM_021072.4:c.212_223dupGCGGCGGCGGCG

Variant names:

• chr5-45695870-T-TCGCCGCCGCCGC
• rs747975797
• NM_021072.4:c.212_223dupGCGGCGGCGGCG

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM4

The NM_021072.4(HCN1):​c.212_223dupGCGGCGGCGGCG​(p.Gly71_Gly74dup) variant causes a conservative inframe insertion change. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type INS_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000011 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: HCN1 NM_021072.4 conservative_inframe_insertion
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.52
• Publications: 1 publications found

Genes affected

HCN1 (HGNC:4845): (hyperpolarization activated cyclic nucleotide gated potassium channel 1) The membrane protein encoded by this gene is a hyperpolarization-activated cation channel that contributes to the native pacemaker currents in heart and neurons. The encoded protein can homodimerize or heterodimerize with other pore-forming subunits to form a potassium channel. This channel may act as a receptor for sour tastes. [provided by RefSeq, Oct 2011]

HCN1 Gene-Disease associations (from GenCC):

• developmental and epileptic encephalopathy, 24

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• generalized epilepsy with febrile seizures plus

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• generalized epilepsy with febrile seizures plus, type 10

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

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

• PM4: Nonframeshift variant in NON repetitive region in NM_021072.4.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_021072.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HCN1	NM_021072.4	MANE Select	c.212_223dupGCGGCGGCGGCG	p.Gly71_Gly74dup	conservative_inframe_insertion	Exon 1 of 8	NP_066550.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HCN1	ENST00000303230.6	TSL:1 MANE Select	c.212_223dupGCGGCGGCGGCG	p.Gly71_Gly74dup	conservative_inframe_insertion	Exon 1 of 8	ENSP00000307342.4
	HCN1	ENST00000673735.1		c.212_223dupGCGGCGGCGGCG	p.Gly71_Gly74dup	conservative_inframe_insertion	Exon 1 of 9	ENSP00000501107.1
	HCN1	ENST00000634658.1	TSL:3	c.212_223dupGCGGCGGCGGCG	p.Gly71_Gly74dup	conservative_inframe_insertion	Exon 1 of 2	ENSP00000489134.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.0000106 AC: 15 AN: 1415360 Hom.: 0 Cov.: 33 AF XY: 0.00000996 AC XY: 7 AN XY: 702546

African (AFR) AF: 0.00 AC: 0 AN: 31432

American (AMR) AF: 0.00 AC: 0 AN: 39240

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 24940

East Asian (EAS) AF: 0.00 AC: 0 AN: 37864

South Asian (SAS) AF: 0.0000122 AC: 1 AN: 81870

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 41108

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5298

European-Non Finnish (NFE) AF: 0.0000128 AC: 14 AN: 1095108

Other (OTH) AF: 0.00 AC: 0 AN: 58500

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy Uncertain:1

Jun 02, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ClinVar contains an entry for this variant (Variation ID: 1005322). 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. This variant has been observed in at least one individual who was not affected with HCN1-related conditions (Invitae). This variant, c.212_223dup, results in the insertion of 4 amino acid(s) of the HCN1 protein (p.Gly71_Gly74dup), 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 HCN1-related conditions.

not provided Uncertain:1

Jul 12, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In-frame insertion of 3 amino acids in a repetitive region with no known function; Has not been previously published as pathogenic or benign to our knowledge

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		6.5

Splicing

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

Other links and lift over

dbSNP: rs747975797; hg19: chr5-45695972;