2-135823999-A-G

Position:

• chr2-135823999-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_002299.4(LCT):​c.809T>C​(p.Ile270Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,458,052 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: LCT NM_002299.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.39

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), LCT. . Gene score misZ 3.1554 (greater than the threshold 3.09). Trascript score misZ 4.9736 (greater than threshold 3.09). GenCC has associacion of gene with congenital lactase deficiency.
• BP4: Computational evidence support a benign effect (MetaRNN=0.19837892).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LCT	NM_002299.4	c.809T>C	p.Ile270Thr	missense_variant	4/17	ENST00000264162.7
LCT	XM_017004088.3	c.809T>C	p.Ile270Thr	missense_variant	4/15

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LCT	ENST00000264162.7	c.809T>C	p.Ile270Thr	missense_variant	4/17	1	NM_002299.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1458052 Hom.: 0 Cov.: 29 AF XY: 0.00000413 AC XY: 3 AN XY: 725706

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 04, 2023

This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 270 of the LCT protein (p.Ile270Thr). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with LCT-related conditions. ClinVar contains an entry for this variant (Variation ID: 1346616). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be tolerated. 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
AlphaMissense	Benign	0.075
BayesDel_addAF	Benign	-0.24	T
BayesDel_noAF	Benign	-0.58
CADD	Benign	16
DANN	Benign	0.94
DEOGEN2	Benign	0.31	T
Eigen	Benign	-0.44
Eigen_PC	Benign	-0.27
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.55	T
M_CAP	Benign	0.0087	T
MetaRNN	Benign	0.20	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.4	L
MutationTaster	Benign	0.99	N
PrimateAI	Benign	0.35	T
PROVEAN	Benign	-0.39	N
REVEL	Benign	0.082
Sift	Benign	0.053	T
Sift4G	Benign	0.22	T
Polyphen		0.0010	B
Vest4		0.34
MutPred		0.56		Gain of disorder (P = 0.0153);
MVP		0.38
MPC		0.29
ClinPred		0.21	T
GERP RS		4.2
Varity_R		0.050
gMVP		0.38

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

Publications

LitVar

Other links and lift over

dbSNP: rs1017932706; hg19: chr2-136581569;