Required for di- and trimethylation at 'Lys-4' of histone H3. Regulates left/right asymmetry of ASE sensory neurons, via its role as a component of the SET2 complex (PubMed:21698137). Component of the SET2 complex (also known as the SET1/COMPASS complex), which contains at least set-2, swd-2.1, cfp-1, rbbp-5, wdr-5.1, dpy-30 and ash-2. Expressed widely during early embryogenesis (PubMed:21698137). Expression is significantly reduced throughout the embryo after formation of the ASE neurons (PubMed:21698137). Expressed in the maternal germline (PubMed:21698137). Strongly reduced di- and trimethylation at 'Lys-4' of histone H3 in embryos and adult germline stem cells. Mutants also display defects in egg laying and fertility with defective germ cell development. RNAi-mediated knockdown disrupts development of the ASE left (ASEL) neuron, causing it to adopt the ASE right (ASER) cell fate (PubMed:21698137).