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What is 1p36 Deletion Syndrome?

1p36 Deletion Syndrome (pronounced one P three six) is a genetic condition in which a small amount of genetic material is missing (deleted) at the tip of the short arm of chromosome 1. 1p36 Deletion Syndrome (also known as Monosomy 1p36) causes birth defects, minor changes in physical appearance and intellectual disabilities of varying degrees. All children with 1p36 Deletion Syndrome are unique; however, they can share many of these common characteristics:

  • Low muscle tone (congenital hypotonia): Infants with 1p36 Deletion Syndrome often have low muscle tone, which may make it difficult for a newborn to suck and swallow. Hypotonia may also delay sitting, crawling and walking. Muscle tone often improves with age and with physical therapy.
  • Seizure disorder: Individuals with 1p36 Deletion Syndrome may have different types of seizures. Most seizure disorders can be controlled with medication.
  • Growth/feeding problems: Infants with this condition often have difficulty gaining weight. Some do no gain weight well because they have difficulty sucking and swallowing, while others may not grow well even though they are eating well. Some older children with 1p36 Deletion Syndrome become overweight. Dietary changes, special feeding techniques or other medical interventions may be needed to manage the growth problems associated with this condition.
  • Characteristic physical features: Young children with 1p36 Deletion Syndrome tend to look similar. They often have a small head, a large fontanel (soft spot), deep-set eyes, short eye openings, a flat nose with a broad nasal tip, a prominent forehead, low set ears, ear asymmetry, a small mouth and a small pointed chin.
  • Developmental delay: Most young children with 1p36 Deletion Syndrome sit up, walk and talk later than usual. Speech is often more delayed than other skills. Many individuals with 1p36 Deletion Syndrome have difficulty talking and may benefit from the use of sign language or assisted communication devices. Early intervention services and intensive speech therapy are recommended to maximize an individual's abilities.
  • Intellectual disability: Older children and adults with 1p36 Deletion Syndrome have some degree of intellectual disability. Some children with 1p36 Deletion Syndrome can talk and assist in their daily care, while others are not verbal and require constant care. Although the degree of intellectual disability may be somewhat dependent on the size of the deletion, there is presently no way to accurately predict what an infant's IQ will be when they grow up.
  • Congenital malformations: Babies with 1p36 Deletion Syndrome may be born with birth defects such as cleft lip, cleft palate, structural heart defects or malformations of the brain. Surgery may help correct some of these problems.
  • Cardiomyopathy: Some infants with 1p36 Deletion Syndrome have infantile dilated cardiomyopathy. With cardiomyopathy, the heart is enlarged and doesn't pump as strongly as it should. When necessary, medication sometimes helps improve cardiac function.
  • Hearing loss:Conductive or sensorineural hearing loss occurs quite frequently in children with 1p36 Deletion Syndrome. Treatment for hearing loss is usually the same as it is for children with other causes of hearing loss.
  • Vision or eye problems: A number of different types of vision and eye problems have been reported in children with 1p36 Deletion Syndrome. Vision problems can usually be improved with glasses or other interventions.
  • Thyroid problems: Children with 1p36 Deletion Syndrome seem to be at an increased risk of developing thyroid problems, the most common being hypothyroidism. Hypothyroidism occurs when the thyroid gland does not make enough of a hormone that is necessary for growth and development. When diagnosed, hypothyroidism can be treated successfully with medication.
  • Behavior problems: A number of behavior problems have been reported in children with 1p36 Deletion Syndrome. These include self-injuring behavior, banging or throwing objects, hitting people and screaming episodes. Child psychiatrists or psychologists can recommend strategies and medications that may help with behavior problems if they arise.
  • Rare complications: Additional, less common findings reported in children with 1p36 Deletion Syndrome include early onset of puberty (precocious puberty), abnormal curvature of the spine (scoliosis), minor vertebral abnormalities, and testes that have not descended into the scrotum at birth (cryptochirdism). Other uncommon medical complications may include neuroblastoma (a type of abdominal tumor that occurs almost exclusively in early childhood). Neuroblastoma is rare and has only been reported in a few children with 1p36 Deletion Syndrome or a chromosome rearrangement involving 1p36.