The skeletal muscle of patients with SAMs [50, 51] and a class I MHC-transgenic mouse model of SAMs [52] exhibit a reduction of AMPD1, which catalyzes the deamination of AMP to IMP and plays an important role in the purine nucleotide cycle. This evidence concerns the gene AMPD1 and short stature-auditory canal atresia-mandibular hypoplasia-skeletal anomalies syndrome.