What are the signs and symptoms of Marshall-Smith syndrome? Marshall-Smith syndrome is characterized by accelerated skeletal maturation, relative failure to thrive, respiratory difficulties, mental retardation, and unusual facies, including wide and prominent forehead, protruding and widely spaced eyes, blue sclerae (the white part of the eye), depressed nasal bridge, a small, upturned nose, and micrognathia. There are often problems with structures in the respiratory tract (such as the larynx and trachea) and this can lead to difficulty with breathing and frequent infections. Pneumonia is common. Severe feeding difficulties may also result. X-rays show advanced bone age and short and conical phalanges (finger and/or toes bones). The Human Phenotype Ontology provides the following list of signs and symptoms for Marshall-Smith syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Accelerated skeletal maturation 90% Anteverted nares 90% Bowing of the long bones 90% Cognitive impairment 90% Depressed nasal bridge 90% Frontal bossing 90% Hyperextensible skin 90% Joint hypermobility 90% Proptosis 90% Respiratory insufficiency 90% Skeletal dysplasia 90% Slender long bone 90% Thin skin 90% Abnormality of the tongue 50% Blue sclerae 50% Bruising susceptibility 50% Conductive hearing impairment 50% Hypertelorism 50% Hypertrichosis 50% Laryngomalacia 50% Open mouth 50% Recurrent fractures 50% Reduced bone mineral density 50% Scoliosis 50% Short nose 50% Aplasia/Hypoplasia of the cerebellum 7.5% Choanal atresia 7.5% Craniosynostosis 7.5% Gingival overgrowth 7.5% Optic atrophy 7.5% Ventriculomegaly 7.5% Agenesis of corpus callosum - Atlantoaxial dislocation - Atria septal defect - Autosomal dominant inheritance - Bullet-shaped middle phalanges of the hand - Cerebral atrophy - Choanal stenosis - Death in childhood - Decreased body weight - Distal widening of metacarpals - Failure to thrive - Glossoptosis - Hearing impairment - Hypoplasia of midface - Hypoplasia of the odontoid process - Intellectual disability - Irregular dentition - Large sternal ossification centers - Low-set ears - Macrogyria - Malar flattening - Motor delay - Muscular hypotonia - Obstructive sleep apnea - Omphalocele - Overfolded helix - Patent ductus arteriosus - Pectus excavatum - Prominence of the premaxilla - Prominent forehead - Pulmonary hypertension - Recurrent aspiration pneumonia - Retrognathia - Shallow orbits - Short distal phalanx of finger - Short mandibular rami - Short philtrum - Short sternum - Sporadic - Synophrys - Tall stature - Thick eyebrow - Umbilical hernia - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.