SAT-062 Twins with a Homozygous Variant of ARNT2, This Is a Known Saudi Mutation (KSM) of Webb- Dattani Syndrome

Webb-Dattani syndrome (WEDAS) is an autosomal recessive disorder caused by mutation in the ARNT2 gene characterized by frontotemporal hypoplasia, globally delayed development, and pituitary and hypothalamic insufficiency. The condition is reported to be associated with consanguinity and with Saudi Arabian ancestry. We presented twin baby girls with developmental delayment seizures, and microcephaly. They have also hypopituitarism in the form of diabetes insipidus and hypocortlisim. also they have cortical blindness. Their brain MRI shows brain atrophic changes and delayed myelination thin corpus callosum,and small pituitary gland ad absence posterior high signal spot and pituitary stalk. Genetic testing by Exome sequencing was done and it shows A homozygous variant of ARNT2 (ARNT2:NM_014862:exon3:c.147-1G>A). One of this twin her condition deteriorated with uncontrolled seizures and spasticity and died at age 22 months. Conclusion: we report another cases of the ARNT2 mutation in a Saudi family illustrating the disease of webb-dattani Syndrome with seizures and hypopituitarism and severe visual impairment and global developmental delayment.