chr2-135833176-CAG-C

Variant names:

• chr2-135833176-CAG-C
• rs386833838
• NM_002299.4:c.653_654delCT

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PVS1 PM2 PP5

The NM_002299.4(LCT):​c.653_654delCT​(p.Ser218CysfsTer6) variant causes a frameshift change. The variant allele was found at a frequency of 0.000000684 in 1,461,702 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (no stars). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 29)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: LCT NM_002299.4 frameshift
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 4.82
• Publications: 6 publications found

Genes affected

LCT (HGNC:6530): (lactase) The protein encoded by this gene belongs to the glycosyl hydrolase 1 family of proteins. The encoded preproprotein is proteolytically processed to generate the mature enzyme. This enzyme is integral to the plasma membrane and has both phlorizin hydrolase activity and lactase activity. Mutations in this gene are associated with congenital lactase deficiency. Polymorphisms in this gene are associated with lactase persistence, in which intestinal lactase activity persists at childhood levels into adulthood. [provided by RefSeq, Jan 2016]

LCT Gene-Disease associations (from GenCC):

• congenital lactase deficiency

  Inheritance: AR Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), PanelApp Australia, Ambry Genetics

ACMG classification

Our verdict: Pathogenic. The variant received 11 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 2-135833176-CAG-C is Pathogenic according to our data. Variant chr2-135833176-CAG-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 56393.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LCT	NM_002299.4	c.653_654delCT	p.Ser218CysfsTer6	frameshift_variant	Exon 2 of 17	ENST00000264162.7	NP_002290.2
LCT	XM_017004088.3	c.653_654delCT	p.Ser218CysfsTer6	frameshift_variant	Exon 2 of 15		XP_016859577.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
LCT	ENST00000264162.7	c.653_654delCT	p.Ser218CysfsTer6	frameshift_variant	Exon 2 of 17	1	NM_002299.4	ENSP00000264162.2

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461702 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 727164

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86252

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111852

Other (OTH) AF: 0.00 AC: 0 AN: 60386

GnomAD4 genome Cov.: 29

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

Congenital lactase deficiency Pathogenic:1

-

Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM)

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		4.8
Mutation Taster		=3/197	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs386833838; hg19: chr2-136590746;