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

Example Input: Polycomb gene silencing requires histone methyltransferase activity of Polycomb repressive complex 2 (PRC2), which methylates lysine 27 of histone H3. Information on how PRC2 works is limited by lack of structural data on the catalytic subunit, Enhancer of zeste (E(Z)), and the paucity of E(z) mutant alleles that alter its SET domain. Here we analyze missense alleles of Drosophila E(z), selected for molecular study because of their dominant genetic effects. Four missense alleles identify key E(Z) SET domain residues, and a fifth is located in the adjacent CXC domain. Analysis of mutant PRC2 complexes in vitro, and H3-K27 methylation in vivo, shows that each SET domain mutation disrupts PRC2 histone methyltransferase. Based on known SET domain structures, the mutations likely affect either the lysine-substrate binding pocket, the binding site for the adenosylmethionine methyl donor, or a critical tyrosine predicted to interact with the substrate lysine epsilon-amino group. In contrast, the CXC mutant retains catalytic activity, Lys-27 specificity, and trimethylation capacity. Deletion analysis also reveals a functional requirement for a conserved E(Z) domain N-terminal to CXC and SET. These results identify critical SET domain residues needed for PRC2 enzyme function, and they also emphasize functional inputs from outside the SET domain.
Example Output: What is the characteristic domain of histone methyltransferases?

Example Input: Fafhrd and the Gray Mouser are two sword-and-sorcery heroes appearing in stories written by American author Fritz Leiber.
Example Output: Who is the author of Fafhrd and the Gray Mouser?

Example Input: Facioscapulohumeral muscular dystrophy (FSHD) is a primary muscle disorder with autosomal dominant inheritance. FSHD was mapped to chromosome 4 locus q35, but the gene is not yet known. It is characterised by progressive, often asymmetric, selective muscular weakness and great clinical variability. The aim of the study was to analyze 62 FSHD cases from 44 Polish families in which the diagnosis was confirmed by DNA analyses. FSHD diagnosis was based on the clinical findings and standardized investigations confirming primary muscular involvement (EMG, muscle biopsy). DNA analysis was based on EcoRI/BlnI restriction enzyme digestion followed by hybridization with P13E-11 molecular probe. In our material, we have found a relatively large percentage (41%) of big deletions (EcoRI/BlnI fragment of 10-15 kb [kilo bases]), which in the majority of cases (67%) was present in isolated cases. In 10 families (23%) the phenotype was assessed as severe. These are cases with the onset before the age of 10 and fast progression. "Middle sized" deletions (EcoRI/BlnI fragment of 16-29 kb) were prevalent in familial cases and present in 57% of families. "Small" deletion was found in one family (EcoRI/BlnI fragment of 30 kb). Somatic mosaicism was confirmed in one case. De novo mutations were shown in 11% of the examined families. The results of this study indicate that the bigger the deletion, the more severe the FSHD course, however there are some exceptions. A similar relationship has been shown by previous research. Molecular analyses are particularly important in atypical and sporadic cases. It is the first genetic presentation of a group of patients' with this kind of dystrophy in the Polish population.
Example Output:
What is the mode of inheritance of Facioscapulohumeral muscular dystrophy (FSHD)?