MLD syndrome

What is MLD syndrome?
MLD is an acronym for Metachromatic Leukodystrophy. MLD is an autosomal recessive genetic disorder which at the moment has no cure. MLD is directly caused by a deficiency of the enzyme Arylsulfatase-A. Without this enzyme sulfatides build up, eventually destroying the myelin sheath of the nervous system. The myelin sheath is a fatty covering that protects nerve fibres. Without it, the nerves in the brain and the peripheral nerves cease to function properly. The incidence of MLD is now estimated to occur in 1 case in 40,000 live births.

Signs and symptoms
The most common initial signs and symptoms in children who develop MLD during the first 2 years of life are, after a period of normal growth and development, abnormal or erratic movements and other changes in the way they move particularly when they are crawling or walking. Speech is also affected and, as many parents have noted, this is one of the unkindest symptoms—not hearing their children’s voices again. As time goes by, limbs can become painful as contractures develop. Fine motor skills are affected, for instance writing, drawing etc. Difficulties in feeding occur and weight loss becomes a significant problem. Many children are tube fed to overcome this. Ultimately, mobility and speech is totally lost and the child becomes bedridden.

Children with MLD syndrome
Children who start to develop symptoms from around 3 to 16 years of age often show initial impairments in fine motor skills and concentration, and may develop behavioural problems, particularly at school.

Diagnosis of MLD syndrome
Unfortunately, as MLD is such a rare disease and health professionals generally see less than one or two cases in their career, these children are frequently diagnosed as cerebral palsy as they initially have problems with walking and toe walking. However, it can be diagnosed with genetic testing. Currently, gene therapy has proved effective, but only for children with early-juvenile MLD who are pre-symptomatic or early-symptomatic, that is having very mild symptoms.