Leber hereditary optic neuropathy (LHON) is a rare but bilaterally blinding disease. Three characteristic disease-causing point mutations, and other less common mutations, are most often found on the mitochondrially encoded genes of NADH-ubiquinone oxidoreductase core subunits (MT-ND). The purpose of this study is to provide an overview of LHON mutations in Southwestern Ontario and to describe the associated demographic and clinical characteristics.

A retrospective genetic and clinical chart review was performed from January 2015 to 2020. Patients were identified within a mitochondrial mutation database and included if a mutation was detected on the MT-ND1, -ND4, or -ND6 genes. A clinical chart review was done on all available patients.

Forty-five of 63 patients identified had classic disease-causing mutations (6.7% m.3460G>A, 44.4% m.11778G>A, and 48.9% m.14484T>C). Several of the remaining 18 patients had rare mutations previously documented in association with LHON. Of the 14 patients with clinical charts accessible for review, 12 had symptomatic disease, and all but one had bilateral optic neuropathies. Nine patients had classic LHON mutations and 3 had possible novel mutations; 7 were males; 9 had final visual acuity ≤ 20/200 in at least one eye; and 6 of those had ≤20/400 in both eyes.

This study adds to the literature on LHON in Canada, and specifically Southwestern Ontario. The demographic and clinical data regarding LHON in this geographic location, as well as possible novel disease-causing mutations, provide important information to aid clinicians in recognizing cases of LHON that may otherwise be disregarded.

Cerebrotendinous xanthomatosis (CTX) belongs to a heterogeneous group of neurological disorders known as autosomal recessive cerebellar ataxias. Low awareness of CTX can result in misdiagnoses in the differential diagnostic process and may limit one’s ability to offer suitable recommendations. While neurodegeneration is a recognized manifestation of CTX, there is scant literature to characterize the nature of cortical symptoms and even less detailing of its associated neurocognitive and neuropsychiatric manifestations.

Based on the lack of representation of CTX in neuropsychological literature, we sought to present a case seen in a 39-year-old patient within our own clinic.

Evaluation of the patient’s neurocognitive functioning revealed global impairment consistent with a CTX diagnosis and neuroimaging findings noting significant cerebellar involvement.

Neuropsychologists are increasingly called upon to make treatment recommendations and provide information that may be helpful in differential diagnosis as part of multidisciplinary teams. Referrals from neurology are common, and it is important for neuropsychologists to be aware of diseases that affect the central nervous system; CTX is one such example. The goal of this case study is to build awareness of this condition and increase interest in a more systematic approach to research and clinical care of this population.