Some conditions known to cause hypotonia include: Congenital – i.e. disease a person is born with (including genetic disorders presenting within 6 months) * Genetic disorders are the most common cause * 22q13 deletion syndrome a.k.a. Phelan–McDermid syndrome * 3-Methylcrotonyl-CoA carboxylase deficiency * Achondroplasia * Aicardi syndrome * Autism spectrum disorders * Canavan disease * Centronuclear myopathy (including myotubular myopathy) * Central core disease * CHARGE syndrome * Cohen syndrome * Costello syndrome * Dejerine–Sottas disease (HMSN Type III) * Down syndrome a.k.a. trisomy 21 — most common * Ehlers–Danlos syndrome * Familial dysautonomia (Riley–Day syndrome) * FG syndrome * Fragile X syndrome * Griscelli syndrome Type 1 (Elejalde syndrome) * Holocarboxylase synthetase deficiency / Multiple carboxylase deficiency * Krabbe disease * Leigh's disease * Lesch–Nyhan syndrome * Marfan's syndrome * Menkes syndrome * Methylmalonic acidemia * Myotonic dystrophy * Niemann–Pick disease * Nonketotic hyperglycinemia (NKH) or Glycine encephalopathy (GCE) * Noonan syndrome * Neurofibromatosis * Patau syndrome a.k.a. trisomy 13 *Pituitary dwarfism/growth hormone deficiency(in adults) *<unk><unk>  syndrome * Rett syndrome * Septo-optic dysplasia (de Morsier syndrome) * Snyder–Robinson syndrome (SRS) * Spinal muscular atrophy (SMA) * Succinic semialdehyde dehydrogenase deficiency (SSADH) * Tay–Sachs disease * Werdnig–Hoffmann syndrome – Spinal muscular atrophy with congenital degeneration of anterior horns of spinal cord. Autosomal recessive *Wiedemann–Steiner syndrome *<unk> ams syndrome * Zellweger syndrome a.k.a. cerebrohepatorenal syndrome * Developmental disability * Cerebellar ataxia (congenital) * Sensory processing disorder * Developmental coordination disorder * Hypothyroidism (congenital) * Hypotonic cerebral palsy * Teratogenesis from in utero exposure to Benzodiazepines Acquired Acquired – i.e. onset occurs after birth * Genetic * Muscular dystrophy (including Myotonic dystrophy) – most common * Metachromatic leukodystrophy * Rett syndrome * Spinal muscular atrophy * Infections * Encephalitis * Guillain–Barré syndrome * Infant botulism * Meningitis * Poliomyelitis * Sepsis * Toxins * Infantile acrodynia (childhood mercury poisoning) * Autoimmunity disorders * Myasthenia gravis – most common * Abnormal vaccine reaction * Celiac disease * Metabolic disorder * Hypervitaminosis * Kernicterus * Rickets * Neurological * Traumatic brain injury, such as the damage that is caused by shaken baby syndrome * Lower motor neuron lesions * Upper motor neuron lesions * Miscellaneous * Central nervous system dysfunction, including cerebellar lesions and cerebral palsy * Hypothyroidism * Sandifer syndrome * Neonatal benzodiazepine withdrawal syndrome in children born to mothers treated in late pregnancy with benzodiazepine medications
symptom of Prader–Willi syndrome
symptom of Scheuermann's disease
symptom of Rotor syndrome
symptom of Klinefelter syndrome
symptom of Klippel–Feil syndrome
symptom of Kallmann syndrome
symptom of Laron syndrome
symptom of Angelman syndrome