Types of MLD - Onset/Progression

There are three types of MLD - Late Infantile, Juvenile and Adult onset. The type of MLD usually remains consistent within a family.* Late Infantile is the most common presentation followed by Juvenile and then Adult.* Some medical journals are describing four type of MLD, making a distinction between early and late juvenile forms of MLD.*

• Late Infantile is characterized by normal development the first 6-18 months followed by a progressive regression that shows first in motor skills, perhaps never learning to walk, or showing a deterioration of balance. The regression will rapidly affect speech, overall mobility, and basic cognitive skills. Often the muscles will painfully cramp up (rigidity), and feeding requires a G-tube or J-tube directly to the digestive system. Paralysis and blindness are often reported with a prognosis of 1-2 years, although today's care often extends that period.

• Juvenile Onset is characterized by normal development with an onset between ages 4-14. The first signs are changes in gait (balance/walking) or cognitive abilities and often a change in unexplainable behavioral outbursts presented by not being able to remember recent events, unable to follow simple sequences. The cognitive skills will continue to decline along with continence control over a period of 4-8 years. Speech ability will also decline during this period. The regression is slower than in the late infantile form, but the pattern is similar ... affecting mobility, eating, speech, and cognitive skills. Eventually the muscle tone is lost and cramping might occur, and swallowing/feeding requires a G-tube or J-tube directly to the digestive system. Paralysis and blindness are often reported with a prognosis of 6-8 years, although today's care often extends that period. There are reports on the MLD Family of a slower degeneration in this group with individuals maintaining mobility and basic cognitive skills 10-12 years after onset.

• Adult Onset is characterized by normal development through puberty, and then symptoms present at some later age - from the 20's through the 40's are what we have seen. As with juvenile onset, the initial adult onset signs are changes in gait (balance/walking) or cognitive abilities and personality. The MLD sufferer might show poor school or work performance, anxious, bewildered, less alert, disorganized, poor judgement, and show declining memory skills. Often this may covered up or compensated for by alcoholism, or similar behaviors. Cognitive, speech, and mobility skills will regress along with a loss of continence over a period of years. There is very little published data about the prognosis of adult onset MLD. Again, the regression is slower than in the juvenile form, but the pattern is similar.