A recent study found a higher incidence of Unverricht-Lundborg disease (ULD), a form of progressive myoclonic epilepsy, in Finland than any other country. The study also found a varying degree of disease progression in all patients along with an increased risk of premature death in patients after the age of 40.
Unverricht-Lundborg disease (ULD), also known as progressive myoclonic epilepsy-1A (EMP1) is a common type of EMP, but a very rare congenital disease worldwide, with high incidence in Finland. Approximately 4 in 100,000 are affected by the disease annually. The disease is of autosomal recessive origin meaning that both parents have to pass on the mutated or defective gene to the offspring for the development of the disease.
Unverricht-Lundborg disease is characterized by episodes of involuntary muscle jerking or twitching or myoclonus that are brought upon by physical exertion, stress, and light.
Although the disease is extremely rare, it has a Finnish heritage and is found to be prevalent in the area. A study conducted as a collaboration between North Karelia Central Hospital, the University of Turku, Kuopio University Hospital, the University of Eastern Finland, and Turku University Hospital was performed with the objective of studying the epidemiology of the disease along with the pathophysiology and course of the disease and the general life expectancy of the disease in Finland.
Method of study
The study led by Sipilä and published in Neurology Journal analyzed the medical data of all patients diagnosed with Unverricht-Lundborg disease in Finland between January 1, 1998, and December 31, 2016.
The data were obtained in combination with the nationwide registers, hospital records, and genetic studies.
Results of the study
Sipilä and her team analyzed the data and found 135 patients affected with ULD, 105 of which were alive in 2016 making the prevalence of Unverricht-Lundborg disease in Finland to be 1.9 cases per 100,000 inhabitants. However, a comparison of different data sources found that not all cases might have been included and there might also be misdiagnosis or underdiagnosis of patients affected by Unverricht-Lundborg disease. This could mean that the prevalence of ULD is higher than determined by the study.
They also found a range for the age of onset between 7 and 14 years, the mean age of onset at 9.4 ± 2.3 years. Furthermore, they found the mean age of death to be 53.9 with a wide range for the age of death between 23.2 and 63.8 years.
The most common cause for death, accounting for 56% of the total deaths, was found to be lower respiratory tract infection. The team of researchers also found that as the patients aged, the risk for premature death increased, especially after the age of 40 years.
The analysis of the data also showed that approximately 10% of all the cases showed a mild progression of the disease, although a high number of them showed severe progression, especially when compared to the disease progression of Unverricht-Lundborg disease patients from Italy. with great variation in the course of the disease development and progression among each patient.