What are the signs and symptoms of GM1 gangliosidosis? There are three general types of GM1 gangliosidosis, which differ in severity but can have considerable overlap of signs and symptoms. Classic infantile (type 1) GM1 gangliosidosis is the most severe type, with onset shortly after birth (usually within 6 months of age). Affected infants typically appear normal until onset, but developmental regression (loss of acquired milestones) eventually occurs. Signs and symptoms may include neurodegeneration, seizures, liver and spleen enlargement, coarsening of facial features, skeletal irregularities, joint stiffness, a distended abdomen, muscle weakness, an exaggerated startle response to sound, and problems with gait (manner of walking). About half of people with this type develop cherry-red spots in the eye. Children may become deaf and blind by one year of age. Affected children typically do not live past 2 years of age. Juvenile (type 2) GM1 gangliosidosis is considered an intermediate form of the condition and may begin between the ages of 1 and 5. Features include ataxia, seizures, dementia, and difficulties with speech. This type progresses more slowly than type 1, but still causes decreased life expectancy (around mid-childhood or early adulthood). Adult (type 3) GM1 gangliosidosis may cause signs and symptoms to develop anywhere between the ages of 3 and 30. Affected people may have muscle atrophy, corneal clouding and dystonia. Non-cancerous skin blemishes may develop on the lower part of the trunk of the body. Adult GM1 is usually less severe and progresses more slowly than other forms of the condition. The Human Phenotype Ontology provides the following list of signs and symptoms for GM1 gangliosidosis. 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) Abnormal diaphysis morphology 90% Abnormality of epiphysis morphology 90% Abnormality of the metaphyses 90% Aplasia/Hypoplasia of the abdominal wall musculature 90% Arthralgia 90% Coarse facial features 90% Depressed nasal ridge 90% Encephalitis 90% Frontal bossing 90% Hyperreflexia 90% Hypertonia 90% Limitation of joint mobility 90% Long philtrum 90% Macrotia 90% Muscular hypotonia 90% Nystagmus 90% Rough bone trabeculation 90% Scoliosis 90% Short stature 90% Skeletal dysplasia 90% Splenomegaly 90% Weight loss 90% Abnormal form of the vertebral bodies 50% Abnormality of the tongue 50% Camptodactyly of finger 50% Gingival overgrowth 50% Hernia of the abdominal wall 50% Hyperlordosis 50% Hypertrichosis 50% Incoordination 50% Mandibular prognathia 50% Opacification of the corneal stroma 50% Seizures 50% Strabismus 50% Tremor 50% Abnormality of the macula 7.5% Abnormality of the retinal vasculature 7.5% Abnormality of the scrotum 7.5% Congestive heart failure 7.5% Optic atrophy 7.5% Recurrent respiratory infections 7.5% Visual impairment 7.5% 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.