20-10412723-A-T

Variant names:

• chr20-10412723-A-T
• rs74315397
• NM_170784.3:c.792T>A

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PVS1 PM2 PP5

The NM_018848.3(MKKS):​c.792T>A​(p.Tyr264*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (no stars). Synonymous variant affecting the same amino acid position (i.e. Y264Y) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MKKS NM_018848.3 stop_gained
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: -3.38
• Publications: 3 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 11 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 20-10412723-A-T is Pathogenic according to our data. Variant chr20-10412723-A-T is described in ClinVar as Pathogenic. ClinVar VariationId is 5312.Status of the report is no_assertion_criteria_provided, 0 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_018848.3. 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
	MKKS	NM_170784.3	MANE Select	c.792T>A	p.Tyr264*	stop_gained	Exon 3 of 6	NP_740754.1
	MKKS	NM_018848.3		c.792T>A	p.Tyr264*	stop_gained	Exon 3 of 6	NP_061336.1
	MKKS	NR_072977.2		n.347-3920T>A		intron	N/A

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MKKS	ENST00000347364.7	TSL:1 MANE Select	c.792T>A	p.Tyr264*	stop_gained	Exon 3 of 6	ENSP00000246062.4
	MKKS	ENST00000399054.6	TSL:1	c.792T>A	p.Tyr264*	stop_gained	Exon 3 of 6	ENSP00000382008.2
	MKKS	ENST00000651692.1		c.792T>A	p.Tyr264*	stop_gained	Exon 4 of 7	ENSP00000498849.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: no assertion criteria provided

Pathogenic	VUS	Benign	Condition
1	-	-	Bardet-Biedl syndrome 6 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.070
CADD	Benign	20
DANN	Benign	0.97
Eigen	Benign	-0.65
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.075	N
PhyloP100		-3.4
Vest4		0.80
GERP RS		-10
Mutation Taster		=1/199	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs74315397; hg19: chr20-10393371;