8-89978245-T-G

Variant names:

• chr8-89978245-T-G
• rs1554566633
• NM_002485.5:c.559A>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_002485.5(NBN):​c.559A>C​(p.Lys187Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000688 in 1,454,392 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict 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. K187E) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.31
• Publications: 0 publications found

Genes affected

NBN (HGNC:7652): (nibrin) Mutations in this gene are associated with Nijmegen breakage syndrome, an autosomal recessive chromosomal instability syndrome characterized by microcephaly, growth retardation, immunodeficiency, and cancer predisposition. The encoded protein is a member of the MRE11/RAD50 double-strand break repair complex which consists of 5 proteins. This gene product is thought to be involved in DNA double-strand break repair and DNA damage-induced checkpoint activation. [provided by RefSeq, Jul 2008]

NBN Gene-Disease associations (from GenCC):

• Nijmegen breakage syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health
• rhabdomyosarcoma

  Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
• idiopathic aplastic anemia

  Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
• prostate cancer

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• hereditary breast carcinoma

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

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

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 32 uncertain in NM_002485.5
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.20317486).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NBN	NM_002485.5	c.559A>C	p.Lys187Gln	missense_variant	Exon 5 of 16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.559A>C	p.Lys187Gln	missense_variant	Exon 5 of 16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.88e-7 AC: 1 AN: 1454392 Hom.: 0 Cov.: 28 AF XY: 0.00000138 AC XY: 1 AN XY: 724120

African (AFR) AF: 0.0000300 AC: 1 AN: 33330

American (AMR) AF: 0.00 AC: 0 AN: 44712

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26080

East Asian (EAS) AF: 0.00 AC: 0 AN: 39540

South Asian (SAS) AF: 0.00 AC: 0 AN: 86014

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5750

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1105412

Other (OTH) AF: 0.00 AC: 0 AN: 60140

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:1

Jun 15, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with an NBN-related disease. This sequence change replaces lysine with glutamine at codon 187 of the NBN protein (p.Lys187Gln). The lysine residue is highly conserved and there is a small physicochemical difference between lysine and glutamine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.062	T
BayesDel_noAF	Benign	-0.33
CADD	Benign	23
DANN	Uncertain	0.98
DEOGEN2	Benign	0.16	T;T;.
Eigen	Benign	0.085
Eigen_PC	Benign	0.20
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Benign	0.80	T;D;T
M_CAP	Benign	0.030	D
MetaRNN	Benign	0.20	T;T;T
MetaSVM	Benign	-0.67	T
MutationAssessor	Uncertain	2.1	M;.;.
PhyloP100		3.3
PrimateAI	Benign	0.33	T
PROVEAN	Benign	-1.7	N;N;N
REVEL	Benign	0.082
Sift	Benign	0.15	T;T;T
Sift4G	Benign	0.10	T;T;.
Polyphen		0.35	B;.;.
Vest4		0.18
MutPred		0.29		Loss of methylation at K187 (P = 0.004);.;.;
MVP		0.81
MPC		0.098
ClinPred		0.76	D
GERP RS		4.8
Varity_R		0.12
gMVP		0.51
Mutation Taster		=87/13	polymorphism

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: rs1554566633; hg19: chr8-90990473;