16-10923236-C-T

Position:

• chr16-10923236-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_000246.4(CIITA):​c.3326C>T​(p.Thr1109Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000685 in 1,460,862 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T1109R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: CIITA NM_000246.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.15

Genes affected

CIITA (HGNC:7067): (class II major histocompatibility complex transactivator) This gene encodes a protein with an acidic transcriptional activation domain, 4 LRRs (leucine-rich repeats) and a GTP binding domain. The protein is located in the nucleus and acts as a positive regulator of class II major histocompatibility complex gene transcription, and is referred to as the "master control factor" for the expression of these genes. The protein also binds GTP and uses GTP binding to facilitate its own transport into the nucleus. Once in the nucleus it does not bind DNA but rather uses an intrinsic acetyltransferase (AT) activity to act in a coactivator-like fashion. Mutations in this gene have been associated with bare lymphocyte syndrome type II (also known as hereditary MHC class II deficiency or HLA class II-deficient combined immunodeficiency), increased susceptibility to rheumatoid arthritis, multiple sclerosis, and possibly myocardial infarction. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2013]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.31206822).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CIITA	NM_000246.4	c.3326C>T	p.Thr1109Met	missense_variant	19/20	ENST00000324288.14

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CIITA	ENST00000324288.14	c.3326C>T	p.Thr1109Met	missense_variant	19/20	1	NM_000246.4	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000799 AC: 2 AN: 250398 Hom.: 0 AF XY: 0.0000148 AC XY: 2 AN XY: 135386

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000685 AC: 10 AN: 1460862 Hom.: 0 Cov.: 33 AF XY: 0.00000688 AC XY: 5 AN XY: 726734

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.0000190

Gnomad4 NFE exome AF: 0.00000630

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000302

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Mar 03, 2022

Variant summary: CIITA c.3326C>T (p.Thr1109Met) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 8e-06 in 250398 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.3326C>T in individuals affected with Bare Lymphocyte Syndrome 2 - CIITA Related and no experimental evidence demonstrating its impact on protein function have been reported. One ClinVar submitter has assessed the variant since 2014: the variant was classified as of uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

MHC class II deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Apr 12, 2022

This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 1109 of the CIITA protein (p.Thr1109Met). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with CIITA-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	0.34
BayesDel_addAF	Uncertain	0.095	D
BayesDel_noAF	Benign	-0.10
CADD	Uncertain	26
DANN	Uncertain	1.0
Eigen	Uncertain	0.39
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Benign	0.57	D
LIST_S2	Uncertain	0.86	D;D;D
M_CAP	Benign	0.061	D
MetaRNN	Benign	0.31	T;T;T
MetaSVM	Benign	-0.40	T
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.52	T
Sift4G	Uncertain	0.0060	D;D;D
Vest4		0.29
MutPred		0.44		.;Loss of sheet (P = 0.0817);.;
MVP		0.87
MPC		1.8
ClinPred		0.74	D
GERP RS		3.6
gMVP		0.67

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1013962316; hg19: chr16-11017093; COSMIC: COSV60855883; COSMIC: COSV60855883;