Diagnostic yield and recognized barriers of an adult neurogenetics clinic

The advent of molecular genetic technologies paved a path for the diagnosis of many neurological disorders. Joint evaluation by a neurologist and a medical genetics specialist can potentially increase diagnostic effectiveness by ensuring the exclusion of non-genetic conditions with similar phenotypes and by rationally selecting appropriate genetic diagnostic tools. Therefore, a monthly adult neurogenetics clinic was established. A retrospective review of medical records of all patients who attended the clinic from April 2015 to March 2019 was conducted. Eighty-two patients were evaluated (age: 47.1 ± 15.7, male: 37(45%), 42 (51%) had a positive family history). Disease duration was typically long (11.4 ± 0.9 years). Futile use of diagnostic modalities was very common (45 (55%) had repeated MRI, 28 (34%) hospitalized for observation in neurologic departments, 12 (14%) had a normal metabolic workup, 4 (5%) with a non-conclusive muscle biopsy, 1 with a normal cerebral angiography). Following clinical evaluation, molecular genetic testing was offered to 67 (82%) patients. In the other 15 (18%), routine workup for the exclusion of non-genetic conditions was not complete; obtainable information regarding family members was missing or that a neurogenetic disorder seemed improbable. Twenty-seven (33%) patients received a definitive diagnosis, either a genetic (23, 28%) or non-genetic (4, 5%). Excluding 4 cases of pre-symptomatic diagnosis, the diagnostic yield was 30%. The adherence to genetic testing recommendations was 62%. The reasons for non-adherence were lack of public funding for the required test (52%) and patient decision not to proceed (48%). Given the frequent futile use of diagnostic modalities, referral of non-genetic conditions with similar phenotypes among neurogenetic disorders, and the complexity of clinical genomic data analysis, a multi-disciplinary neurogenetics clinic seems justified.