Mental retardation 31 is a hereditary neurological condition with extensive dysfunction of the nervous system and developmental delays.
Newborns are 'floppy' with poor muscle tone. Breathing difficulties are often apparent at birth and infants have difficulty feeding which may require placement of a feeding tube. Many infants also have spasms and other evidence of seizures. Generalized muscle weakness is present and facial expression is limited (myopathic facies). Neurologic development is delayed and speech is often limited or absent. Some patients are unable to walk while others have a clumsy, unsteady gait. Learning difficulties are common and some patients have features of autism.
A prominent forehead and a high, arched palate are usually present. The eyelid openings slant upward, the eyes seem far apart, and the upper lids may appear to droop. Strabismus (crossing of the eyes), and nystagmus (purposeless jerkiness of eye movements) and lack of coordinated eye movements are often seen. These eye movements suggest some degree of visual impairment but actual levels of visual acuity have not been reported.
Brain MRI scans reveal extensive abnormalities throughout the nervous system.
A mutation (change in DNA) in a specific gene is responsible for this condition. Since the neurological defects prevent reproduction no pedigrees showing the anticipated autosomal dominant pattern of transmission have been published.
The diagnosis is suggested by the pattern of neurological deficits and the facial characteristics but these are nonspecific and a gene test is necessary to make the diagnosis. It would be expected that neurologists, pediatricians, and others would collaborate in the evaluation and care of these patients. An EEG (electroencephalogram) and MRI of the brain could be helpful.
No treatment is known. Respiratory care and nutrition monitoring are important. Physical therapy and perhaps speech therapy and special education would be of benefit for selected patients. No information on lifespan is available.