Shared heritability of attention-deficit/hyperactivity disorder and autism spectrum disorder

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are both highly heritable neurodevelopmental disorders. Evidence indicates both disorders co-occur with a high frequency, in 20–50% of children with ADHD meeting criteria for ASD and in 30-80% of ASD children meeting criteria for ADHD. This review will provide an overview on all available studies [family based, twin, candidate gene, linkage, and genome wide association (GWA) studies] shedding light on the role of shared genetic underpinnings of ADHD and ASD. It is concluded that family and twin studies do provide support for the hypothesis that ADHD and ASD originate from partly similar familial/genetic factors. Only a few candidate gene studies, linkage studies and GWA studies have specifically addressed this co-occurrence, pinpointing to some promising pleiotropic genes, loci and single nucleotide polymorphisms (SNPs), but the research field is in urgent need for better designed and powered studies to tackle this complex issue. We propose that future studies examining shared familial etiological factors for ADHD and ASD use a family-based design in which the same phenotypic (ADHD and ASD), candidate endophenotypic, and environmental measurements are obtained from all family members. Multivariate multi-level models are probably best suited for the statistical analysis

Advancing the Biobehavioral Research of Fatigue With Genetics and Genomics

PURPOSE: To examine phenotypic considerations in the study of fatigue and to explore significant issues affecting the extension of biobehavioral research of fatigue by the inclusion of genetic and genomic markers. THEORETICAL ORGANIZATION: Fatigue is a condition that has an adverse effect on quality of life that has been a focus of nursing inquiry. Yet, the study of fatigue has been stymied by the lack of phenotypic clarity. To expand the biobehavioral inquiry of fatigue, phenotypic clarity is needed. In addition, examining genomic factors associated with fatigue may help to elucidate the pathophysiology of fatigue and, in the future, lead to targeted interventions that address the molecular basis of fatigue. CONCLUSIONS: Given that nursing has been at the forefront of the study of fatigue, nurse scientists should consider enhancing phenotypic clarity by the development of a case-definition and use of a core measure of fatigue, one that can be augmented by condition- or population-specific measures as needed. Following the establishment of phenotypic clarity, the integration of genomics into biobehavioral research offers an opportunity for further clarity of phenotypes and for theoretical specification of the pathophysiology of conditions such as fatigue. CLINICAL RELEVANCE: The development of targeted interventions for fatigue depend on a more precise definition of fatigue and a better understanding of the biologic processes that contribute to its development and persistence

Fine mapping of candidate regions for bipolar disorder provides strong evidence for susceptibility loci on chromosomes 7q

10.1002/ajmg.b.31151American Journal of Medical Genetics, Part B: Neuropsychiatric Genetics1562168-176AJMG