DNA methylation episignatures are sensitive and specific biomarkers for detection of patients with KAT6A/KAT6B variants.

Accurate diagnosis for patients living with neurodevelopmental disorders is often met with numerous challenges, related to the ambiguity of findings and lack of specificity in genetic variants leading to pathology. Genome-wide DNA methylation analysis has been used to develop highly sensitive and specific 'episignatures' as biomarkers capable of differentiating and classifying complex neurodevelopmental disorders. In this study we describe distinct episignatures for KAT6A syndrome, caused by pathogenic variants in the lysine acetyltransferase A gene (KAT6A), and for the two neurodevelopmental disorders associated with lysine acetyl transferase B (KAT6B). We demonstrate the ability of our models to differentiate between highly overlapping episignatures, increasing the ability to effectively identify and diagnose these conditions.

A sibling study of isolated optic neuropathy associated with novel variants in the ACO2 gene.

Inherited optic neuropathy is a rare cause of debilitating vision loss. It may occur in constellation with other syndromic features of neurological impairment, or present as an isolated finding. We describe a sibling pair, without a family history of vision loss, who developed visual impairment in early childhood consistent with optic neuropathy. Genetic testing identified novel compound heterozygous variants in the aconitase 2 (ACO2) gene. To date, seven families hosting ACO2 variants have been described in the literature. We describe the second family with ACO2 variants to have an isolated optic neuropathy highlighting the importance of including this gene in genomic panels assessing inherited optic neuropathies.

A genetic diagnostic approach to infantile epileptic encephalopathies.

Epileptic encephalopathies are characterized by frequent severe seizures, and/or prominent interictal epileptiform discharges on the electroencephalogram, developmental delay or deterioration, and usually a poor prognosis. The epileptiform abnormalities themselves are believed to contribute to the progressive disturbance in cerebral function. Determining the underlying aetiology responsible for infantile epileptic encephalopathy is a clinical challenge worth undertaking to facilitate advice on the recurrence risk and to allow for the option of prenatal testing, as often this category of epilepsy is associated with devastating hardship for families. This review takes advantage of recently published studies that have identified new genes associated with epilepsy and focuses on known monogenic causes where detection is useful for the process of genetic counselling. Based on the review, we present a diagnostic work-up in order to triage specific genetic testing for infants presenting with an epileptic encephalopathy.