Genetic control of postnatal human brain growth

Abstract

Purpose of review Studies investigating postnatal brain growth disorders inform the biology underlying the development of human brain circuitry. This research is becoming increasingly important for the diagnosis and treatment of childhood neurodevelopmental disorders, including autism and related disorders. Here we review recent research on typical and abnormal postnatal brain growth and examine potential biological mechanisms. Recent findings Clinically, brain growth disorders are heralded by diverging head size for a given age and sex, but are more precisely characterized by brain imaging, postmortem analysis, and animal model studies. Recent neuroimaging and molecular biological studies on postnatal brain growth disorders have broadened our view of both typical and pathological postnatal neurodevelopment. Correlating gene and protein function with brain growth trajectories uncovers postnatal biological mechanisms, including neuronal arborization, synaptogenesis and pruning, and gliogenesis and myelination. Recent investigations of childhood neurodevelopmental and neurodegenerative disorders highlight the underlying genetic programming and experience-dependent remodeling of neural circuitry. Summary In order to understand typical and abnormal postnatal brain development, clinicians and researchers should characterize brain growth trajectories in the context of neurogenetic syndromes. Understanding mechanisms and trajectories of postnatal brain growth will aid in differentiating, diagnosing, and potentially treating neurodevelopmental disorders.

Mixed Neurodevelopmental and Neurodegenerative Pathology inNhe6-Null Mouse Model of Christianson Syndrome

“…The interpretation of brain undergrowth in the mouse mutant is also highly consistent with the clinical observations of postnatal microcephaly and developmental trajectories in early childhood in boys with CS. Postnatal microcephaly is reduction in growth of head circumference in the early postnatal period and is generally construed to reflect undergrowth of brain tissue as a result of decreased neuronal arborization, frequently reflecting organellar biology or gliogenesis ( Passemard et al, 2017 ; van Dyck and Morrow, 2017 ). In some situations, postnatal microcephaly may reflect early aggressive degenerative pathology.…”

The role of the gut microbiota in development, function and disorders of the central nervous system and the enteric nervous system

“…Almost all neurones in the CNS are considered to have formed prior to birth in humans, and the different brain structures and nuclei, as well as the major connections, are established before the end of the perinatal period. 54,55 . Nevertheless, the human brain undergoes dramatic changes during the first two decades of life as a result of changes in connectivity and gliogenesis.…”

“…At birth, around 90% of the cells in the rat brain are neurones, and the non-neuronal cells predominantly increase in number in the second and third postnatal weeks. 56 The size of the brain expands remarkable in the early life; the human brain increases three-to four-fold in size from birth to 6 years of age, 54 and the rat brain increases by more than six-fold from birth to adulthood. 56 Although limited neurogenesis occurs in the subventricular zones adjacent to the lateral ventricle as well as in the subgranular layer of the dentate gyrus in adults, this increased brain size is mostly a result of increased neurite outgrowth, synaptogenesis and gliogenesis.…”

The Predictive Value of Head Circumference Growth during the First Year of Life on Early Child Traits

“…Anomalies in structural and functional development of the brain have been associated with characteristics of certain neurodevelopmental disorders and impairments in child development 1 – 4 . Genetic and biological mechanisms determine prenatal and postnatal brain growth 5 . Genetic profile can alter important biological mechanisms involved in brain growth, resulting in microcephaly or macrocephaly.…”