rs281797258

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM2PP5_Very_Strong

The NM_170784.3(MKKS):c.250C>T(p.His84Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000235 in 1,614,114 control chromosomes in the GnomAD database, including 1 homozygotes. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H84Q) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00022 ( 1 hom., cov: 32)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Consequence

MKKS
NM_170784.3 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4

Conservation

PhyloP100: 9.26

Publications

9 publications found

Variant links:

Genes affected

MKKS (HGNC:7108): (MKKS centrosomal shuttling protein) This gene encodes a protein which shares sequence similarity with other members of the type II chaperonin family. The encoded protein is a centrosome-shuttling protein and plays an important role in cytokinesis. This protein also interacts with other type II chaperonin members to form a complex known as the BBSome, which involves ciliary membrane biogenesis. This protein is encoded by a downstream open reading frame (dORF). Several upstream open reading frames (uORFs) have been identified, which repress the translation of the dORF, and two of which can encode small mitochondrial membrane proteins. Mutations in this gene have been observed in patients with Bardet-Biedl syndrome type 6, also known as McKusick-Kaufman syndrome. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2023]

MKKS Gene-Disease associations (from GenCC):

McKusick-Kaufman syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Orphanet
Bardet-Biedl syndrome 6
Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
Bardet-Biedl syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

MKKS links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 20-10413265-G-A is Pathogenic according to our data. Variant chr20-10413265-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 478890.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MKKS	NM_170784.3 link	c.250C>T	p.His84Tyr	missense_variant	Exon 3 of 6	ENST00000347364.7	NP_740754.1	Q9NPJ1B7Z3W9
MKKS	NM_018848.3 link	c.250C>T	p.His84Tyr	missense_variant	Exon 3 of 6		NP_061336.1	Q9NPJ1B7Z3W9
MKKS	NR_072977.2 link	n.347-4462C>T		intron_variant	Intron 2 of 4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
MKKS	ENST00000347364.7 link	c.250C>T	p.His84Tyr	missense_variant	Exon 3 of 6	1	NM_170784.3	ENSP00000246062.4	Q9NPJ1
MKKS	ENST00000399054.6 link	c.250C>T	p.His84Tyr	missense_variant	Exon 3 of 6	1		ENSP00000382008.2	Q9NPJ1
MKKS	ENST00000651692.1 link	c.250C>T	p.His84Tyr	missense_variant	Exon 4 of 7			ENSP00000498849.1	Q9NPJ1
MKKS	ENST00000652676.1 link	n.458+531C>T		intron_variant	Intron 3 of 6

Frequencies

GnomAD3 genomes

AF:

0.000217

AC:

AN:

152230

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.0353

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251330

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000342

AC:

AN:

1461884

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727246

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000360

AC:

AN:

1112008

Other (OTH)

AF:

0.0000166

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000217

AC:

AN:

152230

Hom.:

Cov.:

AF XY:

0.000215

AC XY:

AN XY:

74378

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41456

American (AMR)

AF:

0.00

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4838

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68046

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.490

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00000985

Hom.:

Bravo

AF:

0.000332

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bardet-Biedl syndrome;C0948368:McKusick-Kaufman syndrome

Pathogenic:1

May 13, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces histidine, which is basic and polar, with tyrosine, which is neutral and polar, at codon 84 of the MKKS protein (p.His84Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with McKusick-Kaufman syndrome (PMID: 10802661, 16104012). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 478890). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on MKKS protein function. Experimental studies have shown that this missense change affects MKKS function (PMID: 18094050, 20498079, 28753627). For these reasons, this variant has been classified as Pathogenic. -

not provided

Pathogenic:1

Nov 21, 2024

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Published functional studies demonstrate a damaging effect: depleted MKKS expression and stability (PMID: 18094050); 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: 18094050, 20498079, 28753627, 31028937, 15772095, 11179009, 12107442, 21044901, 20120035, 10802661, 15637713, 16104012) -

Bardet-Biedl syndrome 6

Pathogenic:1

Feb 19, 2024

Baylor Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Bardet-Biedl syndrome

Pathogenic:1

Mar 20, 2025

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

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: MKKS c.250C>T (p.His84Tyr) results in a conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251330 control chromosomes (gnomAD). c.250C>T has been reported in the literature in multiple individuals affected with McKusick-Kaufman syndrome and co-segregated with the disease (Stone_2000, Nakane_2005). These data indicate that the variant is very likely to be associated with disease. At least two publications report this variant affected the MKKS protein function (Hirayama_2008, Scott_2017). The following publications have been ascertained in the context of this evaluation (PMID: 18094050, 16104012, 28753627, 10802661, 20498079, 9467007). ClinVar contains an entry for this variant (Variation ID: 478890). Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.31

BayesDel_addAF

Pathogenic

0.36

BayesDel_noAF

Pathogenic

0.28

CADD

Uncertain

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.87

D;D

Eigen

Pathogenic

0.91

Eigen_PC

Pathogenic

0.89

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.79

.;T

M_CAP

Benign

0.045

MetaRNN

Uncertain

0.45

T;T

MetaSVM

Uncertain

0.33

MutationAssessor

Pathogenic

3.0

M;M

PhyloP100

9.3

PrimateAI

Uncertain

0.54

PROVEAN

Uncertain

-4.0

D;D

REVEL

Pathogenic

0.72

Sift

Uncertain

0.0010

D;D

Sift4G

Uncertain

0.0030

D;D

Polyphen

1.0

D;D

Vest4

0.69

MutPred

0.92

Loss of disorder (P = 0.138);Loss of disorder (P = 0.138);

MVP

0.95

MPC

0.47

ClinPred

0.99

GERP RS

6.1

Varity_R

0.67

gMVP

0.85

Mutation Taster

=3/97

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over