Genetic Basis of Developmental Disabilities

Developmental disabilities are birth defects that cause lifelong problems with how a body part or system works. Developmental disabilities include nervous system insults affecting how the brain, spinal cord and nervous system function; they cause intellectual disability, including Down syndrome and fragile X syndrome; and they also cause learning and behavioral disorders, such as autism spectrum disorders. At the Kennedy Krieger Institute, approximately 450 inpatients and 13,000 outpatients are seen per year (involving 114,000 visits). For most of these disorders, the underlying molecular cause has not been identified. Some, such as chromosomal disorders, have a strongly genetic basis while others, such as traumatic brain injury, are caused by environmental insults but are nonetheless influenced by the genetic background. The purpose of the present study is to identify chromosomal abnormalities underlying a variety of developmental disabilities. The approach is to obtain blood and saliva from children, and from one or both biological parents (and in some cases from siblings and/or additional relatives). Genomic DNA is purified and assayed on single nucleotide polymorphism (SNP) microarrays and/or by sequencing, including whole genome sequencing. These technologies provide high resolution information about chromosomal changes, and the information provided by the parental (and other relatives') DNA allows an interpretation of whether changes in a child are inherited or occur de novo. The study design includes multiple data analysis procedures to interpret the biological significance of findings of chromosomal changes relative to a child's parents, relative to children with similar diagnoses, relative to children with other chromosomal anomalies, and (in some cases) relative to the chromosomal status of siblings. We will further interpret the significance of the findings relative to the general (apparently normal) population by obtaining publicly available data from apparently normal individuals. ]]>
Inclusion Criteria for SNP Arrays: (1) Participant is under age 18 years; (2) at least one biological parent available to participate. Exclusion Criterion for SNP Array: (1) Patient is in foster care. Inclusion Criteria for Whole Genome Sequencing: (1) Participant is under age 18 years; (2) at least one biological parent available to participate. Exclusion Criterion for Whole Genome Sequencing: (1) Patient is in foster care. Inclusion Criteria for Whole Exome Sequencing: (1) Postmortem samples in which both brain (prefrontal cortex) and either heart or kidney tissue was available. ]]>