Question: What is (are) Dravet syndrome ?
Answer: Dravet syndrome is a severe form of epilepsy. The condition appears during the first year of life as frequent fever-related (febrile) seizures. As the condition progresses, other types of seizures typically occur, including myoclonus and status epilepticus. A family history of either epilepsy or febrile seizures exists in 15 percent to 25 percent of cases. Intellectual development begins to deteriorate around age 2, and affected individuals often have a lack of coordination, poor development of language, hyperactivity, and difficulty relating to others. In 30 to 80 percent of cases, Dravet syndrome is caused by changes in the SCN1A gene, which is required for the proper function of brain cells.
Source: GARD

Question: What are the symptoms of Dravet syndrome ?
Answer: What are the signs and symptoms of Dravet syndrome? The Human Phenotype Ontology provides the following list of signs and symptoms for Dravet 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) Absence seizures - Ataxia - Autosomal dominant inheritance - Cerebral atrophy - Cortical visual impairment - Epileptic encephalopathy - Focal seizures with impairment of consciousness or awareness - Generalized myoclonic seizures - Hemiclonic seizures - Infantile onset - Mental deterioration - Motor delay - Postnatal microcephaly - Status epilepticus - 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