Prader-Willi-like syndrome is a rare, genetic, endocrine disease characterized by manifestations of a Prader-Willi syndrome phenotype (including obesity, hyperphagia, hypotonia, psychomotor delay, intellectual disability, small hands/feet, hypogonadism, growth hormone deficiency and characteristic facial features) ocurring in the absence of 15q11-q13 genomic abnormalities.

Muscular hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle), often involving reduced muscle strength. Hypotonia is characterized by a diminished resistance to passive stretching.