Marshall-Smith syndrome

Marshall-Smith syndrome (MSS) is an extremely rare genetic disorder characterized by accelerated skeletal maturation (advanced bone age), distinctive facial features, and failure to thrive. The condition was first described in 1971 and is caused by heterozygous mutations in the NFIX gene on chromosome 19p13. Marshall-Smith syndrome affects multiple body systems, including the skeletal, respiratory, neurological, and craniofacial systems. Key clinical features include a prominent forehead, shallow orbits with prominent eyes, a small chin (micrognathia), a depressed nasal bridge, and long, thin bones with advanced skeletal maturation disproportionate to the child's chronological age. Many affected individuals have significant respiratory difficulties due to upper airway obstruction, which is a major cause of morbidity and mortality in early life. Children with Marshall-Smith syndrome typically present at birth or in early infancy with low birth weight despite accelerated bone maturation, feeding difficulties, and failure to thrive. Intellectual disability of variable severity is common. Additional features may include blue sclerae, glossoptosis (posterior displacement of the tongue), laryngomalacia or tracheomalacia, short stature despite advanced bone age, and recurrent respiratory infections. Some patients develop kyphoscoliosis and joint contractures. Brain abnormalities, including Chiari malformation, have been reported in some cases. There is no cure for Marshall-Smith syndrome, and management is supportive and multidisciplinary. Treatment focuses on addressing respiratory complications, which may require tracheostomy in severe cases, nutritional support often through gastrostomy tube feeding, and management of orthopedic and developmental issues. Early intervention programs, speech therapy, and physical therapy are important components of care. With improved respiratory management, survival into adolescence and adulthood has become more common, though the long-term prognosis remains guarded. Regular monitoring by a team including pulmonologists, orthopedists, neurologists, and developmental specialists is recommended.

Common questions about Marshall-Smith syndrome