Three subgroups related to the affected region of the NBAS protein that differed significantly regarding main clinical features were explored, including Sec39 (predominant liver phenotype with recurrent acute liver failure), C-terminal (multisystemic phenotype with the presence of short statute, skeletal dysplasia, immunological abnormalities, Pelger-Huët anomaly and optic nerve atrophy), and β-propeller (combined phenotype with RALF and multisystemic phenotype). The gene discussed is NBAS; the disease is skeletal dysplasia.