Homozygosity of a Founder Variant c.1508dupC in DOK7 Causes Congenital Myasthenia With Variable Severity.

Background and Objectives: Description of 15 patients with the same variant in DOK7 causing congenital myasthenic syndrome (CMS). Methods: Nine adult and 6 pediatric patients were studied with molecular genetic and clinical investigations. Results: All patients were identified with the c.1508dupC variant in DOK7, of whom 13 were homozygous and 2 patients compound heterozygous. Only 2 patients had limb girdle phenotype, while all adult patients also had ptosis, ophthalmoplegia, facial weakness, as well as inspiratory stridor. Pediatric patients had severe respiratory insufficiency and feeding difficulties at birth. Discussion: The disease severity in our patients varied extensively from ventilator or wheelchair dependence to mild facial weakness, ptosis, and ophthalmoparesis. Most of the patients had normal transmission in conventional 3 Hz stimulation electrophysiologic studies, making the diagnosis of CMS challenging. Our cohort of adult and pediatric patients expands the phenotype of DOK7 CMS and shows the importance of correct and early diagnosis.

Incidence and Prevalence of Early-Onset Dementia in Finland.

OBJECTIVES: Current epidemiologic data of early-onset dementia (EOD), characterized by the onset of the disease before the age of 65, are notably scarce. METHODS: We evaluated the incidence (from January 2010 to December 2021) and prevalence (on December 31, 2021) of EOD and its subtypes in 2 defined areas in Finland. All visits at the dementia outpatient clinics were manually retrospectively reviewed and reassessed (N = 12,490). RESULTS: In the population aged ≤65 years, crude incidence of EOD was 12.3/100,000 persons at risk/year based on 794 new cases from January 1, 2010, to December 31, 2021. Incidence rates for EOD were 20.5 and 33.7 per 100,000 person years in the age group of 30-64 and 45-64 years, respectively. The prevalence of EOD was 110.4 in the age group of 30-64 years and 190.3 in the age group 45-64. Alzheimer disease (AD) (48.2%) and behavioral variant frontotemporal dementia (12.7%) were the most frequent subtypes. The incidence of AD increased during the follow-up, whereas incidence of other forms of EOD remained stable. DISCUSSION: We found higher incidence rates of EOD than previously reported. Unlike other forms of EOD, the incidence of early-onset AD seems to be increasing.