Humans (Homo sapiens) are the most abundant and widespread species of primates, characterized by bipedality and large, complex brains enabling the development of advanced tools, culture and language.

Sex chromosome abnormalities are a group of disorders that affects the number or the structure of the X and Y chromosomes. Examples include monosomy X or structural abnormalities of the chromosome like isochromosome of the long arm (isochromosome Xq), both leading to Turner syndrome.