Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Let me give you an example: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
The answer to this example can be: In what year did francis, duke of anjou leave the netherlands?
Here is why: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.

OK. solve this:
Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder affecting one in 3,500 individuals. The mutation rate in the NF1 gene is one of the highest known for human genes. Compared to other methods, the protein truncation test (PTT) provides improved efficiency in detecting NF1 mutations which are dispersed throughout the gene which spans 350 kilobases of genomic DNA. We have applied the PTT and subsequent sequence analysis of cloned cDNA to identify mutations in NF1 patients. We report here the identification of two novel (W336X and Q315X), and one recurrent (R304X) mutation located in exon 7 and show that all three premature termination codons lead to skipping of exon 7 in a proportion of the transcripts derived from the mutated allele. Possible mutation-induced alterations of the RNA secondary structure and their impact on skipping of exon 7 of the NF1 gene are explored and discussed.
Answer:
Which is the gene mutated in type 1 neurofibromatosis?