rs137853155

Variant names:

• chr20-10405465-A-T
• rs137853155
• NM_170784.3:c.1495T>A

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PS1 PM2 PP3_Strong

The NM_170784.3(MKKS):​c.1495T>A​(p.Cys499Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 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.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MKKS NM_170784.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 8.40
• Publications: 0 publications found

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

ACMG classification

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

• PS1: Transcript NM_170784.3 (MKKS) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.979

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MKKS	NM_170784.3	c.1495T>A	p.Cys499Ser	missense_variant	Exon 6 of 6	ENST00000347364.7	NP_740754.1
MKKS	NM_018848.3	c.1495T>A	p.Cys499Ser	missense_variant	Exon 6 of 6		NP_061336.1
MKKS	NR_072977.2	n.856T>A		non_coding_transcript_exon_variant	Exon 5 of 5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MKKS	ENST00000347364.7	c.1495T>A	p.Cys499Ser	missense_variant	Exon 6 of 6	1	NM_170784.3	ENSP00000246062.4
MKKS	ENST00000399054.6	c.1495T>A	p.Cys499Ser	missense_variant	Exon 6 of 6	1		ENSP00000382008.2
MKKS	ENST00000651692.1	c.1495T>A	p.Cys499Ser	missense_variant	Exon 7 of 7			ENSP00000498849.1
MKKS	ENST00000652676.1	n.1139T>A		non_coding_transcript_exon_variant	Exon 7 of 7

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
CADD	Uncertain	26
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.76	D;D
Eigen	Pathogenic	0.73
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.71	.;T
M_CAP	Pathogenic	0.30	D
MetaRNN	Pathogenic	0.98	D;D
MetaSVM	Uncertain	0.64	D
MutationAssessor	Pathogenic	3.0	M;M
PhyloP100		8.4
PrimateAI	Benign	0.38	T
PROVEAN	Pathogenic	-5.4	D;D
REVEL	Pathogenic	0.88
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;D
Vest4		0.88
MutPred		0.89		Gain of disorder (P = 0.0056);Gain of disorder (P = 0.0056);
MVP		0.92
MPC		0.57
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.85
gMVP		0.88
Mutation Taster		=26/74	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: rs137853155; hg19: chr20-10386113;