ClinVar Genomic variation as it relates to human health

The GPSM2 c.1473delG (p.Phe492SerfsTer5) variant, also referred to as c.1471delG, results in a frameshift and is predicted to cause a premature truncation of the protein. The p.Phe492SerfsTer5 variant has been reported in three studies in which it is found in a homozygous state in a total of nine patients with GPSM2-related disorders, including in eight individuals (including two sibling pairs) with Chudley-McCullough syndrome (CMS), and in one individual with a recessive form of nonsyndromic hearing loss (Doherty et al. 2012; Schrauwen et al. 2013; Almomani et al. 2013). The p.Phe492SerfsTer5 variant was absent from a single control and is reported at a frequency of 0.00003 in the European (non-Finnish) population of the Exome Aggregation Consortium, though this is based on only two alleles so it is presumed to be rare. Due to the potential impact of frameshift variants and supporting evidence from the literature, this variant is classified as pathogenic for GPSM2-related disorders. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population.

The p.Phe492fs variant in GPSM2 has been previously reported in 6 homozygous ind ividuals with Chudley McCullough syndrome (CMS) and 1 homozygous individual with sensorineural hearing loss, and it segregated in two affected siblings (Almoman i 2013, Doherty 2012, Hendriks 1999, Schrauwen 2013). CMS is characterized by s ensorineural hearing loss, typically in the severe to profound range, with chara cteristic abnormalities on brain MRI. Despite the brain abnormalities found on i maging, individuals with CMS do not typically have cognitive or developmental ab normalities. This variant is predicted to cause a frameshift, which alters the protein?s amino acid sequence beginning at position 492 and leads to a premature termination codon 5 amino acids downstream. This alteration is then predicted t o lead to a truncated or absent protein. In summary, this variant meets our crit eria to be classified as pathogenic for Chudley McCullough syndrome in an autoso mal recessive manner based on the predicted impact of the variant and previously reported affected individuals.

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 23208854, 22578326, 27180139, 23494849, 32445360, 28555434)

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 291707). This premature translational stop signal has been observed in individual(s) with hearing loss (PMID: 23208854). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change creates a premature translational stop signal (p.Phe492Serfs*5) in the GPSM2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GPSM2 are known to be pathogenic (PMID: 22578326, 22987632).