Pure/direct duplications on the long arm of chromosome 4 represent an infrequent chromosomal finding. Description of clinical findings in 30 patients has resulted in defining the 4q-associated phenotype. However, such duplications have not been molecularly or genomically characterized yet, limiting genotype-phenotype correlation. We report on the first two patients with a duplication involving the distal third of 4q that are characterized molecularly and genomically. Clinical features in our patients typical of 4q duplication syndrome included mild intellectual disability, cranial malformation, minor facial dysmorphism, and digital anomaly. Duplication of the segment 4q33-4q34, appears to be the critical region resulting in the phenotype associated with 4q duplication syndrome. The genes GLRA3, GMP6A that are invovled in neurogenesis and HAND2 in craniofacial development, within the duplicated region of 4q, may play a key role in the clinical phenotype. As more reporting on molecular characterization of 4q duplication becomes available, the role of these underlying genes may become clearer.

Dioxin-like molecules have been associated with endocrine disruption and liver disease. To better understand aryl hydrocarbon receptor (AHR) biology, metabolic phenotyping and liver proteomics were performed in mice following ligand-activation or whole-body genetic ablation of this receptor. Male wild type (WT) and Ahr –/– mice (Taconic) were fed a control diet and exposed to 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) (61 nmol/kg by gavage) or vehicle for two weeks. PCB126 increased expression of canonical AHR targets ( Cyp1a1 and Cyp1a2 ) in WT but not Ahr –/– . Knockouts had increased adiposity with decreased glucose tolerance; smaller livers with increased steatosis and perilipin-2; and paradoxically decreased blood lipids. PCB126 was associated with increased hepatic triglycerides in Ahr –/– . The liver proteome was impacted more so by Ahr –/– genotype than ligand-activation, but top gene ontology (GO) processes were similar. The PCB126-associated liver proteome was Ahr -dependent. Ahr principally regulated liver metabolism ( e . g ., lipids, xenobiotics, organic acids) and bioenergetics, but it also impacted liver endocrine response ( e . g ., the insulin receptor) and function, including the production of steroids, hepatokines, and pheromone binding proteins. These effects could have been indirectly mediated by interacting transcription factors or microRNAs. The biologic roles of the AHR and its ligands warrant more research in liver metabolic health and disease.