Two major London paediatric neuromuscular centres carried out a retrospective study of 69 children with RYR1-related myopathy followed up between 1992 and 2019:
- 29 presented a dominant form of myopathy linked to RYR1, 31 a recessive form, six a de novo dominant form and three a form of transmission as yet undefined;
- Onset ranged from birth to seven years;
- The median follow-up was 6.2 years, rising to 14.8 years;
- 15% of children over the age of two did not acquire walking ability, and 7% lost it during follow-up;
- 30% had scoliosis and 17% a stiff spine;
- 22% had respiratory problems and 12% required ventilatory assistance from a median age of seven years;
- the annual fall in vital capacity was -0.2% in recessive forms compared with -1.4% in dominant forms;
- Feeding difficulties were present in 30% of children, more than half of whom were receiving enteral nutrition.
