Marshall-Smith Syndrome is characterized by unusually quick physical growth and bone development (maturation), usually starting before birth. Other symptoms can include respiratory difficulties, mental retardation, and certain physical characteristics. (Note: Marshall-Smith Syndrome is not to be confused with "Marshall" Syndrome, which is very different from "Marshall-Smith" Syndrome.)
In patients with Marshall-Smith Syndrome growth and bone development (maturation) occur faster than normal. The individual is underweight in relation to his or her height and does not thrive well. Other symptoms include diminished muscle tone (hypotonia), muscle weakness, hernias in the abdomen (umbilical hernias), and/or mental retardation. Slow development of voluntary movements (psychomotor retardation) may also occur.
Breathing (respiratory) difficulties commonly occur in patients with Marshall-Smith Syndrome. High-pitched noisy breathing which sounds similar to the wind blowing (stridor), extension of the neck beyond normal limits (hyperextension), or the tongue obstructing the air passage may occur.
Physical characteristics of Marshall-Smith Syndrome include excessive hair growth (hypertrichosis), a long head with a prominent forehead, prominent eyes, and/or an upturned nose with a low nasal bridge. The white of the eye (sclerae) may appear bluish. The angle of the lower jawbone on each side of the face as it joins in the front to form the chin (mandibular ramus) may be smaller than average. Generally, the bones of the fingertips (distal phalanges) are narrow but the rest of the bones in the fingers (proximal and middle phalanges) are broad.
Infrequently, the leaf-shaped structure in the throat which normally prevents food or liquid from passing into the windpipe (epiglottis) may not develop properly in some patients with Marshall-Smith Syndrome. Absent and/or smaller than normal openings leading from the nasal passages into the post-nasal space (choanal atresia and/or stenosis), an abnormal larynx and/or soft cartilage of the larynx (laryngomalacia), a short breastbone (sternum), or a deep crease between the big toe (hallux) and second toe may occur in some patients.
Occasionally, brain abnormalities such as atrophy (cerebral atrophy), larger than normal convolutions of the cerebral cortex (macrogyria), or an absent corpus collosum may occur. (For more information on absence of the corpus collosum, choose “corpus collosum” as your search term in the Rare Disease Database). Defects in the immune system (immunologic defect) are sometimes present. Although rare, some babies with Marshall-Smith Syndrome are born with a sac containing part of the intestines protruding outside the abdominal wall, with the umbilical cord attached (omphalocele).
The exact cause of Marshall-Smith Syndrome is unknown. There is no evidence that it is genetic.
Marshall-Smith Syndrome is a rare disorder present at birth affecting males and females in equal numbers. Symptoms of the syndrome are usually present before birth (prenatal onset).
Treatment of Marshall-Smith Syndrome is symptomatic and supportive. Aggressive treatment of breathing (respiratory) difficulties is necessary. Special education and related services will be necessary during school years.
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Anaesthetic Management of a Child with Marshall-Smith Syndrome. G. Dernedde, et al., Can J Anaesth. (Jul 1998, 45 (7)). Pp. 660-63.
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Marshall-Smith Syndrome: New Radiograhic, Clinical and Pathological Observations. G. F. Eich et al., Radiology, (Oct 1991, 181 (1)). Pp. 183-188.
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