Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_001382391.1(CSPP1):c.2456_2459delAGAA(p.Lys819ArgfsTer21) variant causes a frameshift change. The variant allele was found at a frequency of 0.0000048 in 1,459,410 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.
CSPP1 (HGNC:26193): (centrosome and spindle pole associated protein 1) This gene encodes a centrosome and spindle pole associated protein. The encoded protein plays a role in cell-cycle progression and spindle organization, regulates cytokinesis, interacts with Nephrocystin 8 and is required for cilia formation. Mutations in this gene result in primary cilia abnormalities and classical Joubert syndrome. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. [provided by RefSeq, Apr 2014]
Verdict is Pathogenic. Variant got 18 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 8-67159046-CAGAA-C is Pathogenic according to our data. Variant chr8-67159046-CAGAA-C is described in ClinVar as [Pathogenic]. Clinvar id is 217650.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr8-67159046-CAGAA-C is described in Lovd as [Pathogenic].
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change creates a premature translational stop signal (p.Lys814Argfs*21) in the CSPP1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CSPP1 are known to be pathogenic (PMID: 24360807, 24360808). 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 premature translational stop signal has been observed in individual(s) with Joubert syndrome (PMID: 24360808). ClinVar contains an entry for this variant (Variation ID: 217650). For these reasons, this variant has been classified as Pathogenic. -
Feb 23, 2015
UW Hindbrain Malformation Research Program, University of Washington
Significance: Pathogenic
Review Status: criteria provided, single submitter