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Ataxia and cerebellar anomalies - childhood onset v9.38 PAX6 Achchuthan Shanmugasundram Classified gene: PAX6 as Green List (high evidence)
Ataxia and cerebellar anomalies - childhood onset v9.38 PAX6 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Luke Stuart, there are two unrelated patients with heterozygous PAX6 variants and with evidence ataxia and/or a cerebellar syndrome phenotype. Although PAX6 knockout mice showed a primary role for PAX6 in cerebellar development, but did not recapitulate ataxia phenotype, nor cerebellar phenotype in the context of haploinsufficiency.

There is sufficient evidence available for the association of PAX6 biallelic loss-of-function variants with a severe, prenatal/neonatal-onset neurodevelopmental disorder. However, reported cases were stillborn or died in the neonatal period, with only rare survival despite profound developmental abnormalities. Hence, this phenotype is not relevant for this panel.

Hence, the gene should be demoted to amber and the MOI should be updated to 'MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted'.
Ataxia and cerebellar anomalies - childhood onset v9.38 PAX6 Achchuthan Shanmugasundram Gene: pax6 has been classified as Green List (High Evidence).
Ataxia and cerebellar anomalies - childhood onset v9.37 PAX6 Achchuthan Shanmugasundram Tag Q3_26_demote_amber tag was added to gene: PAX6.
Tag Q3_26_expert_review tag was added to gene: PAX6.
Tag Q3_26_MOI tag was added to gene: PAX6.
Ataxia and cerebellar anomalies - childhood onset v9.37 PAX6 Achchuthan Shanmugasundram Phenotypes for gene: PAX6 were changed from Aniridia, Cerebellar Ataxia, And Mental Retardation to Aniridia, OMIM:106210; cerebellar ataxia, MONDO:0000437
Ataxia and cerebellar anomalies - childhood onset v9.36 PAX6 Achchuthan Shanmugasundram Publications for gene: PAX6 were set to
Ataxia and cerebellar anomalies - childhood onset v9.35 PAX6 Luke Stuart edited their review of gene: PAX6: Changed publications to: 17148041, 8188215, 7951315, 20054790, 19876904, 17417613, 8213068, 16979618, 19876904
Ataxia and cerebellar anomalies - childhood onset v9.35 PAX6 Luke Stuart changed review comment from: Early literature suspected PAX6 as the causative gene for Gillespie syndrome (partial aniridia, cerebellar ataxia, and mental retardation), but direct sequencing repeatedly found no PAX6 mutations in classic Gillespie cases. Linkage analysis in affected families showed the disease trait segregates independently from chromosome 11p markers flanking PAX6 (Glaser et al., 1994; PMID 8188215). The causative gene was identified as ITPR1.

PAX6 biallelic loss-of-function causes a severe, prenatal/neonatal-onset neurodevelopmental disorder characterised by anophthalmia/microphthalmia and major CNS malformations, including agenesis of the corpus callosum, olfactory bulb aplasia/hypoplasia, brainstem hypoplasia, cortical malformations, and cerebellar dysplasia/hypoplasia; reported cases were stillborn or died in the neonatal period, with only rare survival despite profound developmental abnormalities (Glaser et al., 1994, PMID: 7951315; Schmidt-Sidor et al., 2009, PMID: 20054790; Solomon et al., 2010, PMID: 19876904). Thus, biallelic PAX6-related disease is not within scope for the paediatric onset ataxia/ cerebellar anomalies panels.

Isolated reports describe heterozygous PAX6 variants associated with neurological manifestations, including ataxia or cerebellar dysfunction:

Ticho et al., 2006 (PMID: 17148041): A patient described as having "atypical Gillespie syndrome" presented with mild hand tremor and learning disability but no reported ataxia or structural cerebellar abnormalities on neuroimaging. Sequencing identified a heterozygous PAX6 splice-site variant, IVS2+2T>A.
Graziano et al., 2007 (PMID 17595013): described a 9.5-year-old girl with bilateral aniridia, ataxia, and intellectual disability; she carried a de novo heterozygous nonsense variant, PAX6 p.(Trp257Ter).
Dansault et al., 2007 (PMID 17417613): In a large family carrying the c.655A>G p.S74G variant, all affected individuals exhibited a mild but consistent cerebellar syndrome. The most severely affected individual had a clear static cerebellar syndrome. MRI findings included hypoplasia of the anterior commissure and absence of the pineal gland in one individual. Despite the consistent neurological phenotype, no specific structural cerebellar abnormalities were identified.

Conclusion: Two unrelated PAX6 families with heterozygous variants showed evidence ataxia and/or a cerebellar syndrome phenotype, the latter without any recognisable cerebellar malformation. PAX6 knockout mice delineate a primary role of PAX6 in cerebellar development, though are not known to recapitulate an ataxia phenotype, nor cerebellar phenotype in the context of haploinsufficiency (Schmahl et al., 1993; PMID 8213068; Quinn et al., 2007; PMID 16979618)). An amber rating with monoallelic inheritance is proposed.; to: Early literature suspected PAX6 as the causative gene for Gillespie syndrome (partial aniridia, cerebellar ataxia, and mental retardation), but direct sequencing repeatedly found no PAX6 mutations in classic Gillespie cases. Linkage analysis in affected families showed the disease trait segregates independently from chromosome 11p markers flanking PAX6 (Glaser et al., 1994; PMID 8188215). The causative gene was identified as ITPR1.

PAX6 biallelic loss-of-function causes a severe, prenatal/neonatal-onset neurodevelopmental disorder characterised by anophthalmia/microphthalmia and major CNS malformations, including agenesis of the corpus callosum, olfactory bulb aplasia/hypoplasia, brainstem hypoplasia, cortical malformations, and cerebellar dysplasia/hypoplasia; reported cases were stillborn or died in the neonatal period, with only rare survival despite profound developmental abnormalities (Glaser et al., 1994, PMID: 7951315; Schmidt-Sidor et al., 2009, PMID: 20054790; Solomon et al., 2010, PMID: 19876904). A rare paediatric report described a 4-year-old proband with compound heterozygous PAX6 variants (1x missense affecting the paired domain and 1x nonsense); they presented with structural brain anomalies including agenesis of the corpus callosum, hypoplastic pons and vermis (absent inferiorly), possible Dandy-Walker malformation, pituitary and hypothalamic hypoplasia; attribution of these phenotypic features to PAX6 is confounded by the proband's dual diagnosis including trisomy 21 (Solomon et al., 2009 (PMID 19876904).

Isolated reports describe heterozygous PAX6 variants associated with neurological manifestations, including ataxia or cerebellar dysfunction:

Ticho et al., 2006 (PMID: 17148041): A patient described as having "atypical Gillespie syndrome" presented with mild hand tremor and learning disability but no reported ataxia or structural cerebellar abnormalities on neuroimaging. Sequencing identified a heterozygous PAX6 splice-site variant, IVS2+2T>A.
Graziano et al., 2007 (PMID 17595013): described a 9.5-year-old girl with bilateral aniridia, ataxia, and intellectual disability; she carried a de novo heterozygous nonsense variant, PAX6 p.(Trp257Ter).
Dansault et al., 2007 (PMID 17417613): In a large family carrying the c.655A>G p.S74G variant, all affected individuals exhibited a mild but consistent cerebellar syndrome. The most severely affected individual had a clear static cerebellar syndrome. MRI findings included hypoplasia of the anterior commissure and absence of the pineal gland in one individual. Despite the consistent neurological phenotype, no specific structural cerebellar abnormalities were identified.

Conclusion: Two unrelated PAX6 families with heterozygous variants showed evidence ataxia and/or a cerebellar syndrome phenotype, the latter without any recognisable cerebellar malformation. PAX6 knockout mice delineate a primary role of PAX6 in cerebellar development, though are not known to recapitulate an ataxia phenotype, nor cerebellar phenotype in the context of haploinsufficiency (Schmahl et al., 1993; PMID 8213068; Quinn et al., 2007; PMID 16979618)). An amber rating with monoallelic inheritance is proposed.
Ataxia and cerebellar anomalies - childhood onset v9.35 PAX6 Luke Stuart changed review comment from: Early literature suspected PAX6 as the causative gene for Gillespie syndrome (partial aniridia, cerebellar ataxia, and mental retardation), but direct sequencing repeatedly found no PAX6 mutations in classic Gillespie cases. Linkage analysis in affected families showed the disease trait segregates independently from chromosome 11p markers flanking PAX6 (Glaser et al., 1994; PMID 8188215). |The sausative gene was identified as ITPR1.

PAX6 biallelic loss-of-function causes a severe, prenatal/neonatal-onset neurodevelopmental disorder characterised by anophthalmia/microphthalmia and major CNS malformations, including agenesis of the corpus callosum, olfactory bulb aplasia/hypoplasia, brainstem hypoplasia, cortical malformations, and cerebellar dysplasia/hypoplasia; reported cases were stillborn or died in the neonatal period, with only rare survival despite profound developmental abnormalities (Glaser et al., 1994, PMID: 7951315; Schmidt-Sidor et al., 2009, PMID: 20054790; Solomon et al., 2010, PMID: 19876904). Thus, biallelic PAX6-related disease is not within scope for the paediatric onset ataxia/ cerebellar anomalies panels.

Isolated reports describe heterozygous PAX6 variants associated with neurological manifestations, including ataxia or cerebellar dysfunction:

Ticho et al., 2006 (PMID: 17148041): A patient described as having "atypical Gillespie syndrome" presented with mild hand tremor and learning disability but no reported ataxia or structural cerebellar abnormalities on neuroimaging. Sequencing identified a heterozygous PAX6 splice-site variant, IVS2+2T>A.
Graziano et al., 2007 (PMID 17595013): described a 9.5-year-old girl with bilateral aniridia, ataxia, and intellectual disability; she carried a de novo heterozygous nonsense variant, PAX6 p.(Trp257Ter).
Dansault et al., 2007 (PMID 17417613): In a large family carrying the c.655A>G p.S74G variant, all affected individuals exhibited a mild but consistent cerebellar syndrome. The most severely affected individual had a clear static cerebellar syndrome. MRI findings included hypoplasia of the anterior commissure and absence of the pineal gland in one individual. Despite the consistent neurological phenotype, no specific structural cerebellar abnormalities were identified.

Conclusion: Two unrelated PAX6 families with heterozygous variants showed evidence ataxia and/or a cerebellar syndrome phenotype, the latter without any recognisable cerebellar malformation. PAX6 knockout mice delineate a primary role of PAX6 in cerebellar development, though are not known to recapitulate an ataxia phenotype, nor cerebellar phenotype in the context of haploinsufficiency (Schmahl et al., 1993; PMID 8213068; Quinn et al., 2007; PMID 16979618)). An amber rating with monoallelic inheritance is proposed.; to: Early literature suspected PAX6 as the causative gene for Gillespie syndrome (partial aniridia, cerebellar ataxia, and mental retardation), but direct sequencing repeatedly found no PAX6 mutations in classic Gillespie cases. Linkage analysis in affected families showed the disease trait segregates independently from chromosome 11p markers flanking PAX6 (Glaser et al., 1994; PMID 8188215). The causative gene was identified as ITPR1.

PAX6 biallelic loss-of-function causes a severe, prenatal/neonatal-onset neurodevelopmental disorder characterised by anophthalmia/microphthalmia and major CNS malformations, including agenesis of the corpus callosum, olfactory bulb aplasia/hypoplasia, brainstem hypoplasia, cortical malformations, and cerebellar dysplasia/hypoplasia; reported cases were stillborn or died in the neonatal period, with only rare survival despite profound developmental abnormalities (Glaser et al., 1994, PMID: 7951315; Schmidt-Sidor et al., 2009, PMID: 20054790; Solomon et al., 2010, PMID: 19876904). Thus, biallelic PAX6-related disease is not within scope for the paediatric onset ataxia/ cerebellar anomalies panels.

Isolated reports describe heterozygous PAX6 variants associated with neurological manifestations, including ataxia or cerebellar dysfunction:

Ticho et al., 2006 (PMID: 17148041): A patient described as having "atypical Gillespie syndrome" presented with mild hand tremor and learning disability but no reported ataxia or structural cerebellar abnormalities on neuroimaging. Sequencing identified a heterozygous PAX6 splice-site variant, IVS2+2T>A.
Graziano et al., 2007 (PMID 17595013): described a 9.5-year-old girl with bilateral aniridia, ataxia, and intellectual disability; she carried a de novo heterozygous nonsense variant, PAX6 p.(Trp257Ter).
Dansault et al., 2007 (PMID 17417613): In a large family carrying the c.655A>G p.S74G variant, all affected individuals exhibited a mild but consistent cerebellar syndrome. The most severely affected individual had a clear static cerebellar syndrome. MRI findings included hypoplasia of the anterior commissure and absence of the pineal gland in one individual. Despite the consistent neurological phenotype, no specific structural cerebellar abnormalities were identified.

Conclusion: Two unrelated PAX6 families with heterozygous variants showed evidence ataxia and/or a cerebellar syndrome phenotype, the latter without any recognisable cerebellar malformation. PAX6 knockout mice delineate a primary role of PAX6 in cerebellar development, though are not known to recapitulate an ataxia phenotype, nor cerebellar phenotype in the context of haploinsufficiency (Schmahl et al., 1993; PMID 8213068; Quinn et al., 2007; PMID 16979618)). An amber rating with monoallelic inheritance is proposed.
Ataxia and cerebellar anomalies - childhood onset v9.35 PAX6 Luke Stuart reviewed gene: PAX6: Rating: AMBER; Mode of pathogenicity: None; Publications: 17148041, 8188215, 7951315, 20054790, 19876904, 17417613, 8213068, 16979618; Phenotypes: Aniridia (OMIM:106210), cerebellar ataxia (MONDO:0000437); Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Ataxia and cerebellar anomalies - childhood onset v0.5 PAX6 Ellen McDonagh gene: PAX6 was added
gene: PAX6 was added to Ataxia and cerebellar anomalies - narrow panel. Sources: Expert Review Green
Mode of inheritance for gene: PAX6 was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: PAX6 were set to Aniridia, Cerebellar Ataxia, And Mental Retardation