Independent Mammalian Genome Contractions Following the KT Boundary

Although it is generally accepted that major changes in the earth's history are significant drivers of phylogenetic diversification and extinction, such episodes may also have long-lasting effects on genomic architecture. Here we show that widespread reductions in genome size have occurred in multiple lineages of mammals subsequent to the Cretaceous–Tertiary (KT) boundary, whereas there is no evidence for such changes in other vertebrate, invertebrate, or land plant lineages. Although the mechanisms remain unclear, such shifts in mammalian genome evolution may be a consequence of an increase in the efficiency of selection against excess DNA resulting from post-KT population size expansions. Independent historical changes in genome architecture in diverse lineages raise a significant challenge to the idea that genome size is finely tuned to achieve adaptive phenotypic modifications and suggest that attempts to use phylogenetic analysis to infer ancestral genome sizes may be problematical

Neuropsychological functions and psychiatric symptoms in late-onset manifestation of pantothenate kinase-associated neurodegeneration: a clinical case report

Purpose of the study: Pantothenate Kinase-associated Neurodegeneration (PKAN) is a form of Neurodegeneration with brain iron accumulation (NBIA) due to gene mutations. Classical phenotype showed progressive neurological symptoms associated to a characteristic pattern of basal ganglia iron deposits. The atypical case, with adult-onset manifestation, could have neuropsychiatric symptoms with behavioral deficits. We described an adult-onset case of Pantothenate Kinase-associated Neurodegeneration. Materials and methods: The patient underwent neuropsychological and psychiatric evaluation and Magnetic Resonance Imaging, respectively for cognitive and behavioral assessment and to confirm the characteristic findings of this syndrome. Results: The patient showed atypical phenotype of Pantothenate Kinase-associated Neurodegeneration, characterized by language deficits, dixesecutive, and psychiatric manifestations, such as obsessive ideation, impulsivity, and disinhibition. Conclusions: This description could be helpful to a more correct diagnosis and clinical management