17q12 duplication

Alternate names

Chromosome 17q12 duplication syndrome; 17q12 microduplication syndrome; Trisomy 17q12; Recurrent duplication of 17q12; 17q12 microduplication; Dup(17)(q12)

Definition

17q12 duplication occurs when a person has an extra copy of a portion of chromosome 17. Our genetic information is organized in structures called chromosomes. People with 17q12 duplication have an extra piece of genetic information from chromosome 17.

Epidemiology

17q12 duplications appear to be rare.

Cause

• The signs and symptoms of 17q12 duplication are caused by having an extra piece of genetic information on one of the chromosomes.
• Most people have 46 chromosomes in each cell of the body, and the chromosomes come in pairs.
• Therefore, there are two copies of chromosome 17.
• People with 17q12 duplication have an extra portion of one copy of chromosome 17.
• It is not known exactly why the gain of genetic information on chromosome 17 causes the signs and symptoms associated with the duplication.
• It is also not known why there can be such a wide range of symptoms, with some people not having any symptoms at all.

Inheritance

Most people who have 17q12 duplication inherited the chromosomal change from a parent. In many cases, the parent has only mild symptoms of the duplication or no symptoms at all.

When a person who has 17q12 duplication has children, for each child there is a:

• 50% chance to inherit the copy of chromosome 17 with the duplication
• 50% chance to inherit the copy of chromosome 17 without the duplication
• Because the signs and symptoms of 17q12 duplication can vary, the exact signs and symptoms that a child with the duplication may have is not possible to predict.
• In some cases, people with 17q12 duplication are the first people in their families to have the duplication. When a duplication is new in a person and is not inherited from either parent, it is called de novo.

Signs and symptoms

• The signs and symptoms of 17q12 duplication most commonly include intellectual disability and developmental delay.
• Intellectual disability may be mild to severe.
• Developmental delay means that some children may not reach milestones such as sitting, standing, or walking at the times other children do.
• Some children with 17q12 duplication also have speech delay.
• People with the duplication have an increased chance to have behavioral problems including autism and schizophrenia.
• People with 17q12 duplication typically have a smaller head size than other people (microcephaly).
• Some people with the duplication may have seizures, abnormalities of brain structures, or vision problems.
• In rare cases, people with the duplication may have other health concerns such as a heart defect or kidney abnormality.
• People with 17q12 duplication may have a wide range of signs and symptoms caused by the duplication.
• Even people within the same family who have the duplication may have different signs and symptoms from each other.
• This concept is called variable expressivity.
• In some cases, people who have 17q12 duplication may not have any signs or symptoms of the duplication at all.
• This concept is called reduced penetrance.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 30%-79% of people have these symptoms

• Cortical dysplasia

5%-29% of people have these symptoms

• Abnormal vertebral morphology
• Atrial septal defect(An opening in the wall separating the top two chambers of the heart)
• Brachydactyly(Short fingers or toes)
• Broad thumb(Broad thumbs)
• Cleft palate(Cleft roof of mouth)
• Cleft soft palate
• Deeply set eye(Deep set eye)
• Delayed speech and language development(Deficiency of speech development)
• Downslanted palpebral fissures(Downward slanting of the opening between the eyelids)
• Esophageal atresia(Birth defect in which part of esophagus did not develop)
• Facial hypotonia(Decreased facial muscle tone)
• Finger syndactyly
• Glaucoma
• Intellectual disability(Mental deficiency)
• Language impairment
• Micrognathia(Little lower jaw)
• Microphthalmia(Abnormally small eyeball)
• Muscular hypotonia of the trunk(Low muscle tone in trunk)
• Peters anomaly
• Polyhydramnios(High levels of amniotic fluid)
• Seizure
• Self-injurious behavior(Self-injurious behaviour)
• Smooth philtrum
• Synophrys(Monobrow)
• Toe syndactyly(Fused toes)
• Tracheoesophageal fistula
• Triangular face(Face with broad temples and narrow chin)

Diagnosis

• The signs and symptoms of 17q12 duplication overlap greatly with the signs and symptoms of other chromosome duplications or other genetic disorders. Therefore, it would be unlikely that a doctor would suspect a person to have 17q12 duplication based on evaluating a person’s developmental or health history.
• In most cases, the duplication is diagnosed when a doctor orders a genetic test called a chromosomal microarray (CMA).
• This test looks for extra or missing pieces of chromosomes.
• Most people who are diagnosed with 17q12 duplication had a CMA completed based on symptoms such as intellectual disability, developmental delay, or behavioral challenges.

Treatment

• Treatment for 17q12 duplication typically includes physical, occupational, and speech therapies.
• Children with the duplication may also require extra help in school.
• These therapies may help people with the duplication reach their full potentials.
• Other treatments may include behavioral therapies to manage behavioral differences such as autism.
• Other treatments that may be recommended for people with 17q12 duplication include antiepileptic drugs to treat seizures. Evaluations of the eyes, heart, and kidneys may also be recommended to rule out any other health problems.

Prognosis

• The long-term outlook for people with 17q12 duplication can vary because the symptoms associated with the duplication are variable.
• Other than some medical problems that may affect the eyes or rarely the kidneys and heart, people with 17q12 duplication are generally healthy.
• Treatment options such as therapies may be helpful in allowing people with the duplication to reach their full potentials.
• Based on current understanding of the duplication, it is expected that people with 17q12 duplication will have a normal lifespan.

NIH genetic and rare disease info

• NIH info on 17q12 duplication

17q12 duplication is a rare disease.

17q12 duplication Resources
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