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: Mutations of SLC9A6 may cause an X-linked clinical syndrome first described by Christianson in 1999 in which affected males exhibited profound intellectual disability, autism, drug-resistant epilepsy, ophthalmoplegia, mild craniofacial dysmorphism, microcephaly, and ataxia. We describe a child with an SLC9A6 mutation and an electroencephalographic pattern consistent with electrographic status epilepticus of sleep. Our patient's electrographic status epilepticus of sleep resolved after treatment with felbamate. Following treatment, he remained seizure-free but did not make significant or lasting gains in language. Our report extends the clinical epilepsy phenotype in children with SLC9A6 mutations to include electrographic status epilepticus of sleep. In addition, felbamate was an effective treatment for electrographic status epilepticus of sleep in our patient. 
 Question: Mutation of which gene is implicated in the Christianson syndrome?

Ex Output:
slc9a6


Ex Input:
Context: Feia Lacus is one of a number of hydrocarbon seas and lakes found on Saturn's largest moon, Titan. 
 Question: What celestial body can Feia Lacus be found on?

Ex Output:
titan


Ex Input:
Context: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, which causes progressive and eventually fatal loss of motor function. Here, we describe genetic and pathologic characterization of brain tissue banked from 19 ALS patients over nearly 20years at the Department of Anatomy and the Centre for Brain Research, University of Auckland, New Zealand. We screened for mutations in SOD1, TARDBP, FUS, and C9ORF72 genes and for neuropathology caused by phosphorylated TDP-43, dipeptide repeats (DPRs), and ubiquilin. We identified 2 cases with C9ORF72 repeat expansions. Both harbored phosphorylated TDP-43 and DPR inclusions. We show that DPR inclusions can incorporate or occur independently of ubiquilin. We also identified 1 case with a UBQLN2 mutation, which showed phosphorylated TDP-43 and characteristic ubiquilin protein inclusions. This is the first study of ALS genetics in New Zealand, adding New Zealand to the growing list of countries in which C9ORF72 repeat expansion and UBQLN2 mutations are detected in ALS cases. 
 Question: Which human disease is associated with mutated UBQLN2

Ex Output:

amyotrophic lateral sclerosis