Question: What is (are) Schindler disease type 1 ?
Answer: Schindler disease is an inherited condition that primarily causes neurological problems. There are three types of Schindler disease. Schindler disease type 1, also called the infantile type, is the most severe form. Babies with this condition appear healthy a birth, but by the age of 8 to 15 months they stop developing new skills and begin losing skills they had already acquired. As the condition progresses, affected individuals develop blindness and seizures, and eventually lose awareness of their surroundings and become unresponsive. People with this form of the condition usually don't survive past early childhood. Schindler disease type 1 is caused by mutations in the NAGA gene. The condition follows an autosomal recessive pattern of inheritance.
Source: GARD

Question: What are the symptoms of Schindler disease type 1 ?
Answer: What are the signs and symptoms of Schindler disease type 1? The Human Phenotype Ontology provides the following list of signs and symptoms for Schindler disease type 1. 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 pyramidal signs 90% Autism 90% Cataract 90% Cognitive impairment 90% Developmental regression 90% Hearing impairment 90% Hypertonia 90% Muscle weakness 90% Seizures 90% Strabismus 90% Visual impairment 90% Hemiplegia/hemiparesis 50% Hepatomegaly 50% Hyperkeratosis 50% Hypertrophic cardiomyopathy 50% Involuntary movements 50% Muscular hypotonia 50% Nystagmus 50% Optic atrophy 50% Telangiectasia of the skin 50% Vertigo 50% Aplasia/Hypoplasia of the cerebellum 7.5% Lymphedema 7.5% Paresthesia 7.5% Autosomal recessive inheritance - Cortical visual impairment - Generalized amyotrophy - Hyperreflexia - Increased urinary O-linked sialopeptides - Infantile onset - Intellectual disability, severe - Myoclonus - Osteopenia - Spasticity - 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.
Source: GARD

Question: What causes Schindler disease type 1 ?
Answer: What causes Schindler disease type 1? Schindler disease type 1 is caused by mutations in the NAGA gene. This gene provides instructions for making the enzyme alpha-N-acetylgalactosaminidase.This enzyme works in the lysosomes (compartments within cells that digest and recycle materials) to help break down complexes called glycoproteins and glycolipids (sugar molecules attached to certain proteins and fats). More specifically, alpha-N-acetylgalactosaminidase helps remove a molecule called alpha-N-acetylgalactosamine from sugars in these complexes. Mutations in the NAGA gene interfere with the ability of the alpha-N-acetylgalactosaminidase enzyme to perform its role in breaking down glycoproteins and glycoliipids. These substances accumulate in the lysosomes and cause cells to malfunction and eventually die. Cell damage in the nervous system and other tissues and organs of the body leads to the signs and symptoms of Schindler disease type 1.
Source: GARD