Sometimes the first signs of MDC1A are only noted after a few months when children have difficulties in holding their head up or are delayed in meeting motor milestones, such as sitting unaided, crawling or walking.
In children with a partial reduction of merosin, the degree of muscle weakness may be milder, and some may learn to walk independently, albeit delayed. Children who have the ability to walk may lose this ability as they grow older and heavier, as the muscles may be unable to cope with a greater strain. It is also possible that some individuals with partial merosin deficiency may retain the ability to walk, into adulthood.
As the muscles are weak and mobility limited, the child may develop or be born with joint ‘contractures’. This means that the muscle tendons tighten up, and the child is unable to move the limbs or the joints as freely as a healthy child would. Hips are commonly affected with contractures and may sometimes be dislocated. Most children with MDC1A also develop a curvature of the spine (scoliosis) and require specialist advice about promoting appropriate sitting support, bracing and, if required, surgery.
As mentioned above, all children with MDC1A have changes in the white matter of the brain, which are visible on brain MRI imaging by six months of age. This is not usually associated with problems in cognition (the thinking processes in the brain). However, a minority of children with MDC1A experience seizures, which can usually be well controlled with anti-epileptic medication.
Weakness of the respiratory muscles is a common problem in people with MDC1A and can result in frequent chest infections and hypoventilation at night (shallow or slow breathing). These are potentially serious complications that require both prompt recognition and intervention. Nocturnal breathing problems may happen in children of any age and can result in symptoms of daytime sleepiness, morning headaches after awakening, a poor appetite and weight loss.
Another problem frequently encountered by children with MDC1A after the first few years of life is difficulty feeding. This can result in prolonged mealtimes and failure to gain weight normally. For this reason, it is essential to monitor weight and height to ensure children with MDC1A receive enough food and energy. Swallowing problems can occur, as well, since the muscles responsible for swallowing may be weak. For some people with MDC1A, it may be necessary to take nutritional supplements. A small surgical procedure, called a gastrostomy, can be performed which entails inserting a tube directly into the stomach. Gastrostomy tube-feeding ensures children and adults with MDC1A receive an adequate level of nutrition when they cannot consume sufficient calories orally.