Our verdict is Benign. Variant got -8 ACMG points: 2P and 10B. PM2BP4_StrongBP6_ModerateBS1
The NM_022081.6(HPS4):c.*1253G>A variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00124 in 175,478 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).
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]
Very rare variant in population databases, with high coverage;
BP4
Computational evidence support a benign effect (BayesDel_noAF=-0.8).
BP6
Variant 22-26451980-C-T is Benign according to our data. Variant chr22-26451980-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 340971.Status of the report is criteria_provided_single_submitter, 1 stars.
BS1
Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00154 (210/136450) while in subpopulation AFR AF= 0.00494 (187/37834). AF 95% confidence interval is 0.00436. There are 0 homozygotes in gnomad4. There are 85 alleles in male gnomad4 subpopulation. Median coverage is 30. This position pass quality control queck.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -