rs281865473

Positions:

• chr17-46171157-CAA-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 8P and 4B. PVS1 BS2

The NM_015443.4(KANSL1):​c.985_986del​(p.Leu329GlufsTer22) variant causes a frameshift change. The variant allele was found at a frequency of 0.00000958 in 1,461,874 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 35)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: KANSL1 NM_015443.4 frameshift
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1 B:1 O:1
• Conservation: PhyloP100: 6.89

Genes affected

KANSL1 (HGNC:24565): (KAT8 regulatory NSL complex subunit 1) This gene encodes a nuclear protein that is a subunit of two protein complexes involved with histone acetylation, the MLL1 complex and the NSL1 complex. The encoded protein has been implicated in a variety of cellular processes including enhancer regulation, cell proliferation, and mitosis. Mutations in this gene are associated with Koolen-de Vries Syndrome. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• BS2: High AC in GnomAdExome4 at 14 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KANSL1	NM_015443.4	c.985_986del	p.Leu329GlufsTer22	frameshift_variant	2/15	ENST00000432791.7	NP_056258.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KANSL1	ENST00000432791.7	c.985_986del	p.Leu329GlufsTer22	frameshift_variant	2/15	1	NM_015443.4	ENSP00000387393	P4

Frequencies

GnomAD3 genomes Cov.: 35

GnomAD3 exomes AF: 0.0000278 AC: 7 AN: 251476 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135918

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.000397

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461874 Hom.: 0 AF XY: 0.0000138 AC XY: 10 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.000306

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 35

Alfa AF: 0.000102 Hom.: 0

EpiCase AF: 0.000109

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1 Benign:1 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Koolen-de Vries syndrome Pathogenic:2 Uncertain:1 Benign:1 Other:1

Pathogenic, criteria provided, single submitter	clinical testing	Mendelics	May 04, 2022	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 02, 2024	- -
Benign, criteria provided, single submitter	clinical testing;in vitro	Genomic Medicine, Universita Cattolica del Sacro Cuore	Jun 25, 2024	Inherited from healthy father. Patient lacking Koolen-de Vries syndrome (KdVS) phenotype. By cDNA analysis, it has been demonstrated that the variant involves a non-functional KANSL1 pseudogene that can be found in some structural haplotypes (PMID: 22751100, PMID: 22751096, PMID: 33050294). IMPORTANT: this variant has been classified as benign in this case because it affects neither functional allele of the KANSL1 gene. it, instead, involves a duplicated genomic region that includes the first two (or three) exons of the KANSL1 transcript NM_015443.4. On the contrary, it should have been considered pathogenic if it was mapped within either functional copy of the KANSL1 gene (PMID: 26306646). It is not possible to define if the variant affects the duplicated region or the functional KANSL1 gene sequence solely on the basis of genomic DNA sequencing results. This variant is reported in the gnomAD database v4.1.0 with a frequency of 0.000005085 in non-Finnish European population (6 out of 1180044 alleles) and of 0.0002702 (8 out of 29606 alleles) in Ashkenazi Jewish population. We expect it is mismapped in those subjects (who are supposed not to be affected by KdVS) and involves the polymorphic duplication of KANSL1 exon 2. -
not provided, no classification provided	literature only	GeneReviews	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Sep 01, 2017	Likely pathogenicity based on finding it twice in our laboratory: in a 7-year-old male with intellectual disability, dysmorphisms, short stature, strabismus, asymmetric prominent ventricles, possible undermylination, amygdala/hippocampal dysgenesis; in a 3-year-old feale with global delays, hypotonia, dysmorphisms, short stature, microcephaly, congenital heart disease, brain & eye anomalies. However, inheritance was not determined, and of note, the promoter and 5' exons of KANSL1 can be partially duplicated in some individuals. Exome and Sanger data could not distinguish if this change is located in the real KANSL1 gene or the duplicated copy of the gene -

Computational scores

Source: dbNSFP v4.3

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: rs281865473; hg19: chr17-44248523;