Malan syndrome is characterised by faster than normal bone growth, developmental delay and intellectual disability. Facial dysmorphism including a long or triangular face, prominent forehead, flat nasal bridge, deep set eyes, short nose with upturned tip, long philtrum, small open mouth , an everted lower lip and a prominent chin. Visual problems are common and include squint causing double vision, underdeveloped optic nerve and refractive errors. These individuals have large head, long and slender fingers, excessive joint mobility and bony deformities like bent spine and depressed chest bone.
Marshall Smith syndrome is characterized by faster than normal bone growth, difficulties in gaining weight, developmental delay, and intellectual disability. Characteristic facial changes include high forehead, prominent eyes, bluish sclera, short nose, flat midface and small chin. These individuals also have increased body hair and gum hypertrophy and are prone for fractures due to low bone density, respiratory problem due to weak larynx and bony deformities like bent spine.
Some patients can have overlapping features of both these disorders.
Malan syndrome has a milder phenotype but Marshall Smith syndrome, on the other hand, have severe growth failure and early death.
NFIX