Here, we report about reducing body myopathy, associated with a mutation in the four and a half LIM domain 1 gene (FHL1), identified in a 40-year-old woman who was suffering from subtle muscle weakness since the age of six and a limping gait since the age of 22 years.
Because muscle weakness was evident prior to loss of Fhl1 protein and without reducing bodies, our findings indicate that loss of function is responsible for the myopathy in the Fhl1 W122S knock-in mice.
Moreover, immunization of myositis-prone mice with FHL1 aggravated muscle weakness and increased mortality, suggesting a direct link between anti-FHL1 responses and muscle damage.
We found one FHL1 mutation (c.311G>A, p.C104Y) in a boy with rapidly progressive muscle weakness and reducing body myopathy who was initially diagnosed with muscular dystrophy.