Genetic research has been centered mostly on three genera (Fagus, Castanea and Quercus) of the family Fagaceae. The American beech (Fagus grandifolia Ehrh.) genome is estimated at 610 Mbp  and has yet to be sequenced. The number of chromosomes is generally stable within the Fagaceae family (2n = 24), with occasional changes (2n = 24 + 1, 2, 3) resulting from irregular segregation at mitosis . Both Fagus grandifolia and F. sylvatica have the most rudimentary genomes within the family, making their genomes attractive for comparative genomics studies .