Cohen syndrome is an inherited disorder impacting motor skills, mental development, and behavior.
Infants with this condition exhibit slow growth and fail to gain weight at the expected rate. They may display microcephaly (a smaller-than-usual head size) and reduced muscle tone (hypotonia), coupled with remarkably flexible joints that render them “floppy” and unable to control their heads. The developmental challenges progress over time, hindering their ability to achieve milestones like rolling over, sitting up, crawling, and walking. Starting in late childhood, individuals with Cohen syndrome often experience weight gain primarily in the torso, which, without intervention, can lead to obesity while their limbs remain slender. In addition to moderate-to-severe intellectual and motor disabilities, individuals with Cohen syndrome are susceptible to frequent and potentially severe infections due to lower-than-average levels of infection-fighting white blood cells (neutropenia). Cohen syndrome profoundly affects vision, causing severe and progressive issues such as extreme nearsightedness and retinal degeneration.
Cohen syndrome is caused by pathogenic (disease-causing) variants in the VPS13B gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 260 chance to be a carrier.
Other names for this condition are Norio syndrome, obesity-hypotonia syndrome, Pepper syndrome, and Prominent incisors-obesity-hypotonia syndrome.
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Revised September 2023
