6-52022809-G-T

Variant names:

• chr6-52022809-G-T
• rs886042677
• NM_138694.4:c.5372C>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PM5

The NM_138694.4(PKHD1):​c.5372C>A​(p.Pro1791His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,834 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. P1791L) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: PKHD1 NM_138694.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.25
• Publications: 0 publications found

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]

PKHD1 Gene-Disease associations (from GenCC):

• autosomal recessive polycystic kidney disease

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Myriad Women’s Health, Orphanet
• polycystic kidney disease 4

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Laboratory for Molecular Medicine, Genomics England PanelApp
• Caroli disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_138694.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr6-52022809-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 283652.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PKHD1	NM_138694.4	c.5372C>A	p.Pro1791His	missense_variant	Exon 33 of 67	ENST00000371117.8	NP_619639.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PKHD1	ENST00000371117.8	c.5372C>A	p.Pro1791His	missense_variant	Exon 33 of 67	1	NM_138694.4	ENSP00000360158.3
PKHD1	ENST00000340994.4	c.5372C>A	p.Pro1791His	missense_variant	Exon 33 of 61	5		ENSP00000341097.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461834 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727226

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111960

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive polycystic kidney disease Uncertain:1

Oct 01, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. This variant disrupts the p.Pro1791Leu amino acid residue in PKHD1. Other variant(s) that disrupt this residue have been observed in individuals with PKHD1-related conditions (PMID: 19940839), which suggests that this may be a clinically significant amino acid residue. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has been observed in individual(s) with polycystic kidney disease (Invitae). In at least one individual the data is consistent with the variant being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 968085). This variant is not present in population databases (ExAC no frequency). This sequence change replaces proline with histidine at codon 1791 of the PKHD1 protein (p.Pro1791His). The proline residue is moderately conserved and there is a moderate physicochemical difference between proline and histidine.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.18
BayesDel_addAF	Uncertain	0.063	T
BayesDel_noAF	Benign	-0.15
CADD	Benign	20
DANN	Benign	0.91
DEOGEN2	Uncertain	0.65	D;.
Eigen	Benign	0.054
Eigen_PC	Benign	0.14
FATHMM_MKL	Benign	0.59	D
LIST_S2	Benign	0.65	T;T
M_CAP	Benign	0.061	D
MetaRNN	Uncertain	0.43	T;T
MetaSVM	Benign	-0.37	T
MutationAssessor	Uncertain	2.0	M;M
PhyloP100		1.3
PrimateAI	Benign	0.48	T
PROVEAN	Uncertain	-4.3	D;D
REVEL	Uncertain	0.41
Sift	Benign	0.078	T;T
Sift4G	Benign	0.47	T;T
Vest4		0.50
ClinPred		0.93	D
GERP RS		5.7
Varity_R		0.15
gMVP		0.79
Mutation Taster		=28/72	disease causing

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: rs886042677; hg19: chr6-51887607;