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 Q]: Context: Mutations in the solute carrier family 9, subfamily A member 6 (SLC9A6) gene, encoding the endosomal Na+/H+ exchanger 6 (NHE6) are associated with Christianson syndrome, a syndromic form of X-linked intellectual disability characterized by microcephaly, severe global developmental delay, autistic behavior, early onset seizures and ataxia. In a 7-year-old boy with characteristic clinical and neuroimaging features of Christianson syndrome and epileptic encephalopathy with continuous spikes and waves during sleep, we identified a novel splice site mutation (IVS10-1G>A) in SLC9A6. These findings expand the clinical spectrum of the syndrome and indicate NHE6 dysfunction as a new cause of electrical status epilepticus during slow-wave sleep (ESES). 
 Question: Mutation of which gene is implicated in the Christianson syndrome?
[EX A]: slc9a6

[EX Q]: 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 A]: slc9a6

[EX Q]: Context: Brian Cohen is born in a stable next door to the one in which Jesus is born, which initially confuses the three wise men who come to praise the future King of the Jews. Brian grows up an idealistic young man who resents the continuing Roman occupation of Judea. While attending Jesus' Sermon on the Mount, Brian becomes infatuated with an attractive young rebel, Judith. His desire for her and hatred for the Romans lead him to join the "People's Front of Judea", one of many fractious and bickering independence movements, who spend more time fighting each other than the Romans. After several misadventures, and escaping from Pontius Pilate, Brian winds up in a line-up of would-be mystics and prophets who harangue the passing crowd in a plaza. Forced to come up with something plausible in order to blend in and keep the guards off his back, Brian repeats some of what he had heard Jesus say, and quickly attracts a small but intrigued audience. Once the guards have left, Brian tries to put the episode behind him, but he has unintentionally inspired a movement. He grows frantic when he finds that some people have started to follow him around, with even the slightest unusual occurrence being hailed as a miracle. Each of their responses ever growing in fervor and intensity making it harder and harder for him to get away from them. Yet because of the mob's excitement, they end up leaving Brian alone. After which he sees Judith is one who didn't leave, and they then spend the night together. In the morning, Brian, completely naked, opens the curtains to discover an enormous crowd outside his mother's house who proclaim him to be the Messiah. Brian's mother protests, "He's not the Messiah, he's a very naughty boy."; and, "There's no Messiah in here. There's a mess all right, but no Messiah." Yet all of her attempts at dispersing the crowd are rebuffed. Furthermore, once Brian addresses them, he also finds that he is unable to change their minds. His followers are completely committed to their beliefs in and of Brian's divinity. They immediately seize upon everything he says and does as points of doctrine. The hapless Brian finds no solace as people have even mobbed his mother's house. They fling their afflicted bodies at him demanding miracle cures and divine secrets. After sneaking out the back, Brian is then finally captured and scheduled to be crucified. Meanwhile, a huge crowd has assembled outside the palace. Pilate (together with the visiting Biggus Dickus) tries to quell the feeling of revolution by granting them the choice of one person to be pardoned. The crowd, however, shouts out names containing the letter "r", mocking Pilate's rhotacistic speech impediment. Eventually, Judith appears in the crowd and calls for the release of Brian, which the crowd echoes since the name also contains an "r". Pilate agrees to "welease Bwian". His order is eventually relayed to the guards, but in a scene that parodies the climax of the film Spartacus, various crucified people all claim to be "Brian of Nazareth" and the wrong man is released. Various other opportunities for a reprieve for Brian are denied as, one by one, his "allies" (including Judith and his mother) step forward to explain why they are leaving the "noble freedom fighter" hanging in the hot sun. Hope is renewed when a crack suicide squad from the "Judean People's Front" (not to be confused with the People's Front of Judea) come charging towards the Romans, but rather than fighting to release Brian or the other prisoners, they commit mass suicide as a political protest. Condemned to a long and painful death, Brian finds his spirits lifted by his fellow sufferers, who break into song with "Always Look on the Bright Side of Life."[6] 
 Question: Which organization does Brian join ?
[EX A]:
people's front of judea