What Is Cohen Syndrome?

Cohen syndrome, caused by mutations in the VPS13B gene, is an inherited condition that affects motor skills, mental development, and behavior. Infants with the condition grow slowly and do not gain weight at the normal rate. They may have a smaller-than-expected head size (microcephaly) and decreased muscle tone (hypotonia) with unusually flexible joints. Infants can feel floppy, like a rag doll, when lifted, and cannot control their heads. Over time, they have difficulty learning to roll over, sit up, crawl, and walk. Beginning in late childhood, people with Cohen syndrome may begin to put on weight in the torso. Without intervention, they can become obese, although their arms and legs remain slender. Patients with Cohen syndrome have distinct facial features.

People with Cohen syndrome show moderate-to-severe intellectual and motor disability that remain constant and do not become progressively worse over time. They are prone to frequent and potentially severe infections because they have a lower-than-average level of certain infection-fighting white blood cells (neutropenia).

Cohen syndrome generally causes severe, progressive vision problems, notably extreme nearsightedness and degeneration of the retina. People with the condition often become functionally, if not entirely, blind. They also tend to be unusually friendly and cheerful, even towards strangers. As a result, parents must be extra vigilant about their child's personal safety.

How Common Is Cohen Syndrome?

The exact prevalence of Cohen syndrome is unknown. It has been reported in fewer than 1000 people worldwide, although more cases likely exist. It is most common in a small Amish community in Ohio, where it affects an estimated 1 in 500 people. It is also more common in Finland.

How Is Cohen Syndrome Treated?

There is no cure for Cohen syndrome, but early intervention with physical, occupational, and speech therapy can address symptoms like joint laxity, clumsiness, and developmental delays. Children with nearsightedness need glasses, while those with retinal degeneration benefit from training for the visually impaired.

In order to prevent recurrent infections, people with Cohen syndrome should be monitored throughout their lives for a low white blood cell count.

What Is the Prognosis for a Person with Cohen Syndrome?

The exact effect of Cohen syndrome on one's lifespan is unclear. Some people with the disease are known to be alive in their fifties.

Other names for
Cohen syndrome

  • Cohen syndrome
  • Hypotonia, obesity, and prominent incisors
  • Norio syndrome
  • Pepper syndrome


  • Budisteanu et al., 2010, Maedica, 5(1):56-61, PMID: 21977120
  • OMIM: Online Mendelian Inheritance in Man, OMIM [216550], 2016, https://www.omim.org/entry/216550
  • Wang et al., 2016, https://www.ncbi.nlm.nih.gov/books/NBK1482/