Best Answer: Chordata refers to the presence of a nerve chord running from the head to the back, which may or may not be accompanied by vertebrae. All animals with backbones are members of the chordate phylum, but not all chordates have bones (lancelets and tunicates are chordates lacking real bones).
Angelman syndrome (AS) is a genetic disorder that causes developmental delay, intellectual disability, speech problems, seizures (epilepsy), and problems with movement and balance (ataxia).ngelman syndrome (AS) is a severe neurodevelopmental disorder caused by maternal deficiency of the imprinted gene UBE3A. Individuals with AS suffer from intellectual disability, speech impairment, and motor dysfunction. Currently there is no cure for the disease.
MELAS is a rare genetic disorder which results in stroke and dementia. MELAS is an abbreviation that stands for Mitochondrial Encephalopathy, Lactic acidosis, and Stroke-like episodes. MELAS syndrome is caused by mutations in the genetic material (DNA) in the mitochondria. While most of our DNA is in the chromosomes in the cell nucleus, some of our DNA is in another important structure called the mitochondrion (plural: mitochondria).