Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM2PP2PP3_Strong
The NM_001368894.2(PAX6):āc.703C>Gā(p.Gln235Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.
PAX6 (HGNC:8620): (paired box 6) This gene encodes paired box protein Pax-6, one of many human homologs of the Drosophila melanogaster gene prd. In addition to a conserved paired box domain, a hallmark feature of this gene family, the encoded protein also contains a homeobox domain. Both domains are known to bind DNA and function as regulators of gene transcription. Activity of this protein is key in the development of neural tissues, particularly the eye. This gene is regulated by multiple enhancers located up to hundreds of kilobases distant from this locus. Mutations in this gene or in the enhancer regions can cause ocular disorders such as aniridia and Peter's anomaly. Use of alternate promoters and alternative splicing results in multiple transcript variants encoding different isoforms. Interestingly, inclusion of a particular alternate coding exon has been shown to increase the length of the paired box domain and alter its DNA binding specificity. Consequently, isoforms that carry the shorter paired box domain regulate a different set of genes compared to the isoforms carrying the longer paired box domain. [provided by RefSeq, Mar 2019]
PAX6 Gene-Disease associations (from GenCC):
aniridia 1
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae)
PAX6-related ocular dysgenesis
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
Our verdict: Likely_pathogenic. The variant received 7 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PP2
Missense variant in the PAX6 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 75 curated pathogenic missense variants (we use a threshold of 10). The gene has 15 curated benign missense variants. Gene score misZ: 2.8175 (below the threshold of 3.09). Trascript score misZ: 3.256 (above the threshold of 3.09). GenCC associations: The gene is linked to Peters anomaly, diabetes mellitus, aniridia-cerebellar ataxia-intellectual disability syndrome, foveal hypoplasia-presenile cataract syndrome, aniridia 1, PAX6-related ocular dysgenesis, coloboma, ocular, autosomal dominant, isolated optic nerve hypoplasia, autosomal dominant keratitis, isolated aniridia.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.95
ā ļø The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.
African (AFR)
AF:
0.00
AC:
0
AN:
33480
American (AMR)
AF:
0.00
AC:
0
AN:
44724
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26136
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39698
South Asian (SAS)
AF:
0.00
AC:
0
AN:
86258
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
53418
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5768
European-Non Finnish (NFE)
AF:
8.99e-7
AC:
1
AN:
1112006
Other (OTH)
AF:
0.00
AC:
0
AN:
60392
ā ļø The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.