Associazione Italiana Rett

Following the recent domestication process of the European rabbit (Oryctolagus cuniculus), many different breeds and lines, distinguished primarily by exterior traits such as coat colour, fur structure and body size and shape, have been constituted. In this study, we genotyped, with a high-density single-nucleotide polymorphism panel, a total of 645 rabbits from 10 fancy breeds (Belgian Hare, Champagne d'Argent, Checkered Giant, Coloured Dwarf, Dwarf Lop, Ermine, Giant Grey, Giant White, Rex and Rhinelander) and three meat breeds (Italian White, Italian Spotted and Italian Silver). ADMIXTURE analysis indicated that breeds with similar phenotypic traits (e.g. coat colour and body size) shared common ancestries. Signatures of selection using two haplotype-based approaches (iHS and XP-EHH), combined with the results obtained with other methods previously reported that we applied to the same breeds, we identified a total of 5079 independent genomic regions with some signatures of selection, covering about 1777 Mb of the rabbit genome. These regions consistently encompassed many genes involved in pigmentation processes (ASIP, EDNRA, EDNRB, KIT, KITLG, MITF, OCA2, TYR and TYRP1), coat structure (LIPH) and body size, including two major genes (LCORL and HMGA2) among many others. This study revealed novel genomic regions under signatures of selection and further demonstrated that population structures and signatures of selection, left into the genome of these rabbit breeds, may contribute to understanding the genetic events that led to their constitution and the complex genetic mechanisms determining the broad phenotypic variability present in these untapped rabbit genetic resources.

Charcot‐Marie‐Tooth disease (CMT) is a genetic neuropathy characterized by a length‐dependent degeneration of motor and sensory nerve fibers. Whereas all authors agree that weakening starts from the intrinsic foot muscles, there is still controversy whether the tibialis anterior muscle (TA) is weak or not in the early stages of the disease. To know this could be important either to understand how the cavus deformity develops or, consequently, to adopt surgical (tendon transfers) and conservative (orthotics, physiotherapy) strategies for prevention or early correction. We measured the power of TA in 110 feet of 62 patients (41 CMT1A, 1 CMT1B, 9 CMT1 without genetic evaluation, 5 CMTX, and 6 CMT2) fitting in the first two stages of the functional classification proposed by Vinci and Perelli. Thirty‐one feet were at stage 1 (forefootdrop or mild footdrop: leg‐sole angle >90< = 100) and 79 at stage 2 (same as stage 1 plus foot rotation on the longitudinal axis: heel angle <0 or >10). Muscle strength was measured by the manual muscle testing and scores according to the Medical Research Council scale. TA power graded 5/5 in 87 (79.1%) feet, 4/5 in 17 (15.5%) and 2/5 in 6 (5.4%). TA was strong (MRC 4/5 and 5/5) in the large majority (94.6%) of the feet in the two earlier stages of the disease. Interestingly, the 6 patients with weaker TA had CMT2. These results support our hypothesis that, in the earliest phase of CMT, foot rotation is due to a stronger and hyperactivated TA, which compensates the footdrop caused by the deficit of the metatarsophalangeal joint stabilization and, in many cases, is not balanced by the weak peroneal muscles.