Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Ex Input:
Context: Mowat-Wilson syndrome (MWS) is characterized by severe mental retardation with seizures, specific facial dysmorphism, Hirschsprung disease, anomalies of the corpus callosum, and genitourinary and cardiac malformations. The cause of MWS is a de novo mutation in the ZEB2 gene. This report describes a Turkish boy who was clinically diagnosed with MWS and had his diagnosis confirmed by molecular analysis of the ZEB2 gene. The investigation identified a heterozygous complex rearrangement in exon 8 of ZEB2, specifically a 48-nucleotide deletion and a 44-nucleotide insertion that caused a frameshift. MWS is a relatively newly identified disorder, and even MWS patients without Hirschsprung disease can be diagnosed easily based on clinical findings alone. 
 Question: Which gene is responsible for the development of the Mowat-Wilson syndrome?

Ex Output:
zeb2


Ex Input:
Context: Can you name some fossils? How about dinosaur bones or dinosaur footprints? Animal skeletons, teeth, shells, coprolites (otherwise known as feces), or any other remains or traces from a living creature that becomes rock is a fossil. The same processes that formed these fossils also created some of our most important energy resources, fossil fuels. Coal, oil, and natural gas are fossil fuels. Fossil fuels come from living matter starting about 500 million years ago. Millions of years ago, plants used energy from the Sun to form sugars, carbohydrates, and other energy-rich carbon compounds. As plants and animals died, their remains settled on the ground on land and in swamps, lakes, and seas (Figure 1.1). Over time, layer upon layer of these remains accumulated. Eventually, the layers were buried so deeply that they were crushed by an enormous mass of earth. The weight of this earth pressing down on these plant and animal remains created intense heat and pressure. After millions of years of heat and pressure, the material in these layers turned into chemicals called hydrocarbons (Figure 1.2). Hydrocarbons are made of carbon and hydrogen atoms. This molecule with one carbon and four hydrogen atoms is methane. Hydrocarbons can be solid, liquid, or gaseous. The solid form is what we know as coal. The liquid form is petroleum, or crude oil. Natural gas is the gaseous form. The solar energy stored in fossil fuels is a rich source of energy. Although fossil fuels provide very high quality energy, they are non-renewable. Click image to the left or use the URL below. URL: 
 Question: hydrocarbons in solid form are called _________________.

Ex Output:
coal


Ex Input:
Context: The first step in the management of restless legs syndrome (RLS) is to identify, and if possible to treat any condition which might cause or worsen RLS, such as iron deficiency or some drug treatments. The patients suffering from RLS should be prompted to keep a healthy sleep schedule. Drug treatment should be restricted to patients with a clear clinical diagnosis, decided on an individual basis, when the clinical impact is serious. Four drug classes are central to the treatment of RLS: dopaminergic agents, some antiepileptics, opioids, and benzodiazepines. Dopaminergic agonists are the treatment of choice, especially when daily treatment is indicated, or if the symptoms are severe. Two dopaminergic agonists are licensed in France for the treatment of RLS: ropinirole (Adartrel) and pramipexole (Sifrol). After initiation of treatment, the patients should benefit from a regular follow-up in order to evaluate the efficacy of treatment and to identify possible side-effects. Special care should be given to the detection of augmentation, a phenomenon characterized by a paradoxical worsening of the symptoms with treatment. Some particular conditions, such as RLS comorbid with renal insufficiency, during pregnancy, and in the child are discussed. 
 Question: Which deficiency is the cause of restless leg syndrome?

Ex Output:

iron