chr22-26477019-T-A

Position:

• chr22-26477019-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_022081.6(HPS4):​c.250A>T​(p.Ile84Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I84V) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: HPS4 NM_022081.6 missense
• Clinical Significance: Uncertain significance no assertion criteria provided U:1
• Conservation: PhyloP100: -2.99

Genes affected

HPS4 (HGNC:15844): (HPS4 biogenesis of lysosomal organelles complex 3 subunit 2) This gene encodes a protein component of biogenesis of lysosome-related organelles complexes (BLOC). BLOC complexes are important for the formation of endosomal-lysosomal organelles such as melanosomes and platelet dense granules. Mutations in this gene result in subtype 4 of Hermansky-Pudlak syndrome, a form of albinism. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Aug 2012]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.08887276).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HPS4	NM_022081.6	c.250A>T	p.Ile84Leu	missense_variant	4/14	ENST00000398145.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HPS4	ENST00000398145.7	c.250A>T	p.Ile84Leu	missense_variant	4/14	1	NM_022081.6	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: no assertion criteria provided

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

-

The HPS4 p.Ile84Leu variant was not identified in the literature nor was it identified in dbSNP, ClinVar or in the following control databases: the 1000 Genomes Project, the NHLBI GO Exome Sequencing Project, or the Genome Aggregation Database (March 6, 2019, v2.1.1). The p.Ile84 residue is not conserved in mammals and computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) do not suggest a high likelihood of impact to the protein; however, this information is not predictive enough to rule out pathogenicity. The variant occurs outside of the splicing consensus sequence and 1 of 4 in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) predict a greater than 10% difference in splicing; this is not very predictive of pathogenicity. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.26
BayesDel_addAF	Benign	-0.011	T
BayesDel_noAF	Benign	-0.25
CADD	Benign	0.0010
DANN	Benign	0.73
DEOGEN2	Benign	0.10	T;.;T;.
Eigen	Benign	-1.9
Eigen_PC	Benign	-2.1
FATHMM_MKL	Benign	0.12	N
LIST_S2	Benign	0.59	.;T;T;T
M_CAP	Uncertain	0.086	D
MetaRNN	Benign	0.089	T;T;T;T
MetaSVM	Benign	-0.84	T
MutationAssessor	Uncertain	2.0	M;.;M;.
MutationTaster	Benign	1.0	N;N;N;N
PrimateAI	Benign	0.29	T
PROVEAN	Benign	-1.5	N;N;N;N
REVEL	Benign	0.27
Sift	Benign	0.41	T;T;T;T
Sift4G	Benign	0.089	T;T;T;.
Polyphen		0.021	B;B;B;.
Vest4		0.32
MutPred		0.35		Gain of helix (P = 0.0854);.;Gain of helix (P = 0.0854);Gain of helix (P = 0.0854);
MVP		0.58
MPC		0.13
ClinPred		0.051	T
GERP RS		-11
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.049
gMVP		0.50

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr22-26872985;