rs1557256416

Variant names:

• chrX-148652027-A-T
• rs1557256416
• NM_002025.4:c.76A>T
• AFF2 p.Lys26*

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_002025.4(AFF2):​c.76A>T​(p.Lys26*) variant causes a stop gained change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: AFF2 NM_002025.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 4.65
• Publications: 0 publications found

Genes affected

AFF2 (HGNC:3776): (ALF transcription elongation factor 2) This gene encodes a putative transcriptional activator that is a member of the AF4\FMR2 gene family. This gene is associated with the folate-sensitive fragile X E locus on chromosome X. A repeat polymorphism in the fragile X E locus results in silencing of this gene causing Fragile X E syndrome. Fragile X E syndrome is a form of nonsyndromic X-linked cognitive disability. In addition, this gene contains 6-25 GCC repeats that are expanded to >200 repeats in the disease state. Alternate splicing results in multiple transcript variants.[provided by RefSeq, Jul 2016]

AFF2 Gene-Disease associations (from GenCC):

• FRAXE intellectual disability

  Inheritance: XL Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), G2P
• non-syndromic X-linked intellectual disability

  Inheritance: XL Classification: DEFINITIVE Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 12 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant X-148652027-A-T is Pathogenic according to our data. Variant chrX-148652027-A-T is described in ClinVar as Pathogenic. ClinVar VariationId is 521344.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_002025.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	AFF2	NM_002025.4	MANE Select	c.76A>T	p.Lys26*	stop_gained	Exon 2 of 21	NP_002016.2	P51816-1
	AFF2	NM_001169123.2		c.76A>T	p.Lys26*	stop_gained	Exon 2 of 21	NP_001162594.1	P51816-5
	AFF2	NM_001169122.2		c.76A>T	p.Lys26*	stop_gained	Exon 2 of 20	NP_001162593.1	P51816-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	AFF2	ENST00000370460.7	TSL:5 MANE Select	c.76A>T	p.Lys26*	stop_gained	Exon 2 of 21	ENSP00000359489.2	P51816-1
	AFF2	ENST00000342251.7	TSL:1	c.76A>T	p.Lys26*	stop_gained	Exon 2 of 20	ENSP00000345459.4	P51816-3
	AFF2	ENST00000370457.9	TSL:1	c.76A>T	p.Lys26*	stop_gained	Exon 2 of 20	ENSP00000359486.6	P51816-6

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 23

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	Inborn genetic diseases (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.62
CADD	Pathogenic	36
DANN	Uncertain	1.0
FATHMM_MKL	Uncertain	0.94	D
PhyloP100		4.7
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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

dbSNP: rs1557256416;

hg19: chrX-147733548;