X-134498407-CC-TA

Variant names:

• chrX-134498407-CC-TA
• NM_000194.3:c.503_504delCCinsTA
• HPRT1 p.Thr168Ile

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PS1 PM1 PP2

The NM_000194.3(HPRT1):​c.503_504delCCinsTA​(p.Thr168Ile) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Pathogenic in ClinVar. Synonymous variant affecting the same amino acid position (i.e. T168T) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 23)
• Consequence: HPRT1 NM_000194.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 5.67
• Publications: 0 publications found

Genes affected

HPRT1 (HGNC:5157): (hypoxanthine phosphoribosyltransferase 1) The protein encoded by this gene is a transferase, which catalyzes conversion of hypoxanthine to inosine monophosphate and guanine to guanosine monophosphate via transfer of the 5-phosphoribosyl group from 5-phosphoribosyl 1-pyrophosphate. This enzyme plays a central role in the generation of purine nucleotides through the purine salvage pathway. Mutations in this gene result in Lesch-Nyhan syndrome or gout.[provided by RefSeq, Jun 2009]

HPRT1 Gene-Disease associations (from GenCC):

• Lesch-Nyhan syndrome

  Inheritance: XL Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, G2P, Ambry Genetics, Orphanet
• hypoxanthine guanine phosphoribosyltransferase partial deficiency

  Inheritance: XL Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PS1: Transcript NM_000194.3 (HPRT1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 7 uncertain in NM_000194.3
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 31 curated pathogenic missense variants (we use a threshold of 10). The gene has 1 curated benign missense variants. Gene score misZ: 2.3178 (below the threshold of 3.09). Trascript score misZ: NaN (below the threshold of 3.09). GenCC associations: The gene is linked to Lesch-Nyhan syndrome, hypoxanthine guanine phosphoribosyltransferase partial deficiency.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000194.3. 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
	HPRT1	NM_000194.3	MANE Select	c.503_504delCCinsTA	p.Thr168Ile	missense	N/A	NP_000185.1	A0A140VJL3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HPRT1	ENST00000298556.8	TSL:1 MANE Select	c.503_504delCCinsTA	p.Thr168Ile	missense	N/A	ENSP00000298556.7	P00492
	HPRT1	ENST00000969780.1		c.548_549delCCinsTA	p.Thr183Ile	missense	N/A	ENSP00000639839.1
	HPRT1	ENST00000969779.1		c.539_540delCCinsTA	p.Thr180Ile	missense	N/A	ENSP00000639838.1

Frequencies

GnomAD3 genomes Cov.: 23

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 23

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		5.7

Splicing

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

hg19: chrX-133632437;