An assessment of brain transcriptome differences between zebrafish siblings homozygous, heterozygous, and wild type for a loss-of-function mutation in mfn2. Overall design: Six families of siblings were generated by mating of pairs of zebrafish heterozygous for the hu3528 allele of the mfn2 gene (https://doi.org/10.1371/journal.pone.0067276). Each family was raised from a single mating event. Each family was derived from a different pair of heterozygous fish. The mfn2 homozygous mutant fish have lower fitness than other genotypes and so, at 2.5 months of age, the siblings of a family were genotyped using PCRs on DNA from tail biopsies, and then separated into wild type, homozygous and heterozygous groups that were subsequently raised in separate tanks in the same recirculated water system. At 4 months of age the fish were humanely euthanised using tricaine and their brains were removed for RNA purification. The brains of two male and two female fish from each tank were pooled before RNA purification of total RNA using Trizol (Invitrogen) and Direct-Zol (Zymo Research). RNA-seq was performed on the Illumina HiSeq platform (Illumina, San Diego, California, USA) by Novogene (UK) Company Limited, Cambridge, UK. Libraries were provided as paired-end (2x150bp) reads for n = 6 from each of the three genotypes. Library sizes ranged between 40,530,508 and 69,496,372 reads.