16-88810420-T-TA

Position:

• chr16-88810420-T-TA

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_Strong PM2 PP5

The ENST00000378364.8(APRT):​c.321+2dupT variant causes a splice donor, intron change. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: APRT ENST00000378364.8 splice_donor, intron
• Clinical Significance: Pathogenic no assertion criteria provided P:2
• Conservation: PhyloP100: 5.14

Genes affected

APRT (HGNC:626): (adenine phosphoribosyltransferase) Adenine phosphoribosyltransferase belongs to the purine/pyrimidine phosphoribosyltransferase family. A conserved feature of this gene is the distribution of CpG dinucleotides. This enzyme catalyzes the formation of AMP and inorganic pyrophosphate from adenine and 5-phosphoribosyl-1-pyrophosphate (PRPP). It also produces adenine as a by-product of the polyamine biosynthesis pathway. A homozygous deficiency in this enzyme causes 2,8-dihydroxyadenine urolithiasis. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

APRT (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.24493554 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3.4, offset of 0 (no position change), new splice context is: aagGTtaag. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 16-88810420-T-TA is Pathogenic according to our data. Variant chr16-88810420-T-TA is described in ClinVar as [Pathogenic]. Clinvar id is 18295.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APRT	NM_000485.3	c.321+2dupT		splice_donor_variant, intron_variant		ENST00000378364.8	NP_000476.1
APRT	NM_001030018.2	c.321+2dupT		splice_donor_variant, intron_variant			NP_001025189.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APRT	ENST00000378364.8	c.321+2dupT		splice_donor_variant, intron_variant		1	NM_000485.3	ENSP00000367615.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: no assertion criteria provided

Submissions by phenotype

Adenine phosphoribosyltransferase deficiency Pathogenic:2

Pathogenic, no assertion criteria provided	literature only	OMIM	Jan 01, 1997	- -
Pathogenic, no assertion criteria provided	literature only	APRT Deficiency Research Program of the Rare Kidney Stone Consortium, Landspitali, National University Hospital of Iceland	Sep 01, 2020	- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.79		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.23		Position offset: 13
DS_DL_spliceai		0.79		Position offset: 3

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

Publications

LitVar

Other links and lift over

dbSNP: rs281860263; hg19: chr16-88876828;