chr6-51934157-T-C

Variant names:

• chr6-51934157-T-C
• rs1554144226
• NM_138694.4:c.6074A>G

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_138694.4(PKHD1):​c.6074A>G​(p.Tyr2025Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000684 in 1,461,654 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: PKHD1 NM_138694.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:3
• Conservation: PhyloP100: 3.31

Genes affected

PKHD1 (HGNC:9016): (PKHD1 ciliary IPT domain containing fibrocystin/polyductin) The protein encoded by this gene is predicted to have a single transmembrane (TM)-spanning domain and multiple copies of an immunoglobulin-like plexin-transcription-factor domain. Alternative splicing results in two transcript variants encoding different isoforms. Other alternatively spliced transcripts have been described, but the full length sequences have not been determined. Several of these transcripts are predicted to encode truncated products which lack the TM and may be secreted. Mutations in this gene cause autosomal recessive polycystic kidney disease, also known as polycystic kidney and hepatic disease-1. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a domain G8 1 (size 121) in uniprot entity PKHD1_HUMAN there are 9 pathogenic changes around while only 3 benign (75%) in NM_138694.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.946
• PP5: Variant 6-51934157-T-C is Pathogenic according to our data. Variant chr6-51934157-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 552140.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=3, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PKHD1	NM_138694.4	c.6074A>G	p.Tyr2025Cys	missense_variant	Exon 37 of 67	ENST00000371117.8	NP_619639.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PKHD1	ENST00000371117.8	c.6074A>G	p.Tyr2025Cys	missense_variant	Exon 37 of 67	1	NM_138694.4	ENSP00000360158.3
PKHD1	ENST00000340994.4	c.6074A>G	p.Tyr2025Cys	missense_variant	Exon 37 of 61	5		ENSP00000341097.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000684 AC: 10 AN: 1461654 Hom.: 0 Cov.: 32 AF XY: 0.00000963 AC XY: 7 AN XY: 727148

Gnomad4 AFR exome AF: 0.0000598

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: 0.00

Gnomad4 NFE exome AF: 0.00000630

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:3 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Autosomal recessive polycystic kidney disease Pathogenic:2 Uncertain:1

Apr 06, 2021

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: PKHD1 c.6074A>G (p.Tyr2025Cys) results in a non-conservative amino acid change located in the G8 domain (IPR019316) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251546 control chromosomes (gnomAD and publication data). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.6074A>G has been reported in the literature in at-least one case of a proband affected with features of autosomal recessive polycystic kidney disease to include kidney and liver involvement (PKD/CHF), pulmonary hypoplasia, oligohydramnios and perinatal death (Krall_2014). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. One ClinVar submitter (evaluation after 2014) cites the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

May 30, 2017

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 21, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt PKHD1 protein function. ClinVar contains an entry for this variant (Variation ID: 552140). This missense change has been observed in individual(s) with polycystic kidney disease (PMID: 24162162). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 2025 of the PKHD1 protein (p.Tyr2025Cys). -

Polycystic kidney disease 4 Uncertain:2

Aug 28, 2017

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 22, 2023

Neuberg Centre For Genomic Medicine, NCGM

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The missense c.6074A>G(p.Tyr2025Cys) variant in PKHD1 gene has been reported previously in compound heterozygous state in individual(s) affected with polycystic kidney disease (Krall P, et al. 2014). The p.Tyr2025Cys variant is absent in gnomAD Exomes. This variant has been reported to the ClinVar database as Likely Pathogenic / Uncertain Significance. Multiple lines of computational evidences (Polyphen - Probably damaging, SIFT - Damaging and MutationTaster - Disease causing) predict a damaging effect on protein structure and function for this variant. The reference amino acid at this position on PKHD1 gene is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. The amino acid Tyr at position 2025 is changed to a Cys changing protein sequence and it might alter its composition and physico-chemical properties. Additional functional studies will be required to prove the pathogenicity of this variant conclusively. For these reasons, this variant has been classified as a Variant of Uncertain Significance (VUS). -

not provided Pathogenic:1

May 11, 2023

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in the presence of a second PKHD1 variant, phase unknown, in a patient with polycystic kidney disease in published literature (Krall et al., 2014); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 24162162) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.26
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.91	D;.
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.87	D;D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.95	D;D
MetaSVM	Uncertain	0.70	D
MutationAssessor	Pathogenic	3.5	M;M
PrimateAI	Uncertain	0.52	T
PROVEAN	Pathogenic	-7.0	D;D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0010	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	D;D
Vest4		0.92
MutPred		0.66		Gain of catalytic residue at P2024 (P = 0.0073);Gain of catalytic residue at P2024 (P = 0.0073);
MVP		0.99
MPC		0.41
ClinPred		1.0	D
GERP RS		4.3
Varity_R		0.84
gMVP		0.92

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554144226; hg19: chr6-51798955;