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Fetal anomalies v2.10 RAC3 Arina Puzriakova Tag Q2_22_rating was removed from gene: RAC3.
Fetal anomalies v2.10 RAC3 Arina Puzriakova edited their review of gene: RAC3: Added comment: The rating of this gene has been updated to Green and the mode of inheritance set to 'MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted' following NHS Genomic Medicine Service approval.; Changed rating: GREEN
Fetal anomalies v2.9 RAC3 Arina Puzriakova Source Expert Review Green was added to RAC3.
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Fetal anomalies v1.851 RAC3 Arina Puzriakova Phenotypes for gene: RAC3 were changed from Abnormality of brain morphology; Abnormal muscle tone; Neurodevelopmental delay; Intellectual disability to Neurodevelopmental disorder with structural brain anomalies and dysmorphic facies, OMIM:618577
Fetal anomalies v1.850 RAC3 Arina Puzriakova Classified gene: RAC3 as Amber List (moderate evidence)
Fetal anomalies v1.850 RAC3 Arina Puzriakova Added comment: Comment on list classification: New gene added by Rhiannon Mellis (GOSH). Following curation and clinical review it has been agreed that the associated phenotype is fetally-relevant and therefore this gene should be promoted to Green at the next GMS panel update.
Fetal anomalies v1.850 RAC3 Arina Puzriakova Gene: rac3 has been classified as Amber List (Moderate Evidence).
Fetal anomalies v1.849 RAC3 Arina Puzriakova Tag Q2_22_rating tag was added to gene: RAC3.
Fetal anomalies v1.827 RAC3 Rhiannon Mellis gene: RAC3 was added
gene: RAC3 was added to Fetal anomalies. Sources: Literature,Expert Review,NHS GMS
Mode of inheritance for gene: RAC3 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: RAC3 were set to 30293988; 29276006
Phenotypes for gene: RAC3 were set to Abnormality of brain morphology; Abnormal muscle tone; Neurodevelopmental delay; Intellectual disability
Mode of pathogenicity for gene: RAC3 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: RAC3 was set to GREEN
Added comment: This gene already has sufficient evidence for Green rating on the ID panel (see below) and now adding evidence (from NHS GMS testing) for prenatal phenotype to support Green rating for the Fetal Anomalies panel also: A RAC3 likely pathogenic missense variant has been identified postnatally in a baby that presented prenatally with absent corpus callosum, bilateral ventriculomegaly, cerebellar and brainstem hypoplasia detected on fetal ultrasound and MRI. The variant is judged by the child's clinical team to be causative of the clinical and radiological features in the child.

Copied from Green review on Intellectual Disability panel by Konstantinos Varvagiannis:

PMID: 30293988 reports on 5 individuals (from 4 different families) with de novo missense variants in RAC3. All individuals demonstrated structural anomalies on brain MRI (notably agenesis/dysgenesis of the corpus callosum, variable degrees of polymicrogyria and ventricular anomalies) as well as shared non-specific neurological features including abnormal muscular tone, global developmental delay and severe to profound intellectual disability. Feeding difficulties were observed in 4/5 patients.

All variants reported are missense and are presumed to result in constitutive protein activation, as suggested by previous observations either in RAC3 [eg. the p.(Gln61Leu) mutation] or the highly homologous RAC1 and RAC2. According to the authors this is further supported by the fact that Rac3 -/- mice do not show a severe phenotype while missense variants are underrepresented in the ExAC database (z=1.97) as opposed to loss-of-function variants (pLI=0.04 / probability of loss-of-function intolerance).

Of the 3 SNVs reported, 2 variants were in adjacent amino-acid positions [p.(Gln61Leu) and p.(Glu62Lys)]. The latter variant was found in 2 half-sibs born to different fathers, due to suspected maternal gonadal mosaicism (variant absent in all sequencing reads in the maternal DNA sample). The specific variant was also found in a further affected individual from an unrelated family.

Finally, as the authors point out a further individual with de novo RAC3 missense variant [p.(Ala59Gly)] was reported previously in an individual with thin corpus callosum and global developmental delay, although the phenotype was felt to be more reminiscent of Robinow syndrome (PMID: 29276006).
Sources: Literature, Expert Review, NHS GMS