Rare Nephrology News

Disease Profile

15q13.3 microduplication syndrome

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of onset

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ICD-10

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Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

15q13.3 microduplication; Chromosome 15q13.3 duplication syndrome; Chromosome 15q13.3 microduplication syndrome;

Summary

15q13.3 microduplication syndrome is a rare chromosomal disorder. Our genetic information is organized in structures called chromosomes. People with 15q13.3 microduplication syndrome have an extra piece of genetic information on the long arm (q arm) of chromosome 15. Some people with this duplication do not have any medical or behavioral problems. Other people may have developmental delayintellectual disability, communication difficulties, behavioral and psychiatric problems (such as autistic features, emotional instability, attention-deficit hyperactivity disorder (ADHD), schizophrenia), feeding problems, difficulty sleeping (insomnia), low muscular tone (hypotonia) and seizures.[1] Some people with this syndrome also have cleft palate.[2] The duplication contains the CHRNA7 gene, which is believed to cause the the behavioral abnormalities and the cleft palate.[3]

When the duplication is inherited from a parent, it is inherited in an autosomal dominant manner. A chromosome abnormality may be suspected if a child has feeding problems, developmental delay, intellectual disability, or behavioral problems. Genetic testing using chromosomal microarray (CMA) may confirm the diagnosis. Treatment options may include physicaloccupational, and speech therapies, as well as medications to treat the specific problems seen in each person.[1]

Symptoms

The first signs of 15q13.3 microduplication syndrome may be present in infancy or early childhood. These may include not meeting developmental milestones such as sitting, standing, or walking, at the ages other children do (developmental delay). In some cases, children also have low muscle tone (hypotonia). Some children with the syndrome begin speaking later than other children (speech delay) or have trouble communicating. Infants with 15q13.3 microduplication syndrome have difficulty feeding, and children may want to eat more food than they need (overeating) as they get older.[1][4]

People with 15q13.3 microduplication syndrome may have intellectual disability. In most cases, intellectual disability is mild if it is present, but some people with the syndrome have had more severe intellectual disability. People with the syndrome are more likely to have behavioral challenges including autism, attention difficulties, and schizophrenia.[1][5]

Some children with 15q13.3 microduplication syndrome struggle to sleep at night (insomnia). Other health problems that may be associated with the syndrome include having multiple seizures (epilepsy).[1] One study found that 15q13.3 microduplication syndrome may be associated with cleft lip or palate.[2]

The problems associated with 15q13.3 microduplication syndrome can vary widely, even among members of the same family. This concept is called variable expressivity. In some cases, people who have 15q13.3 microduplication syndrome may not have any medical, developmental, or behavioral problems related to the syndrome. This concept is called reduced penetrance.[1] Because only a small number of people with 15q13.3 microduplication syndrome have been reported, it is not known if there are other medical, developmental, or behavioral problems that may be associated with the syndrome.[1][4]

Cause

15q13.3 microduplication syndrome is caused by having an extra piece of genetic information (duplication) 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 15. People with 15q13.3 microduplication syndrome have an extra copy of a small piece of chromosome 15. Specifically, this duplicated piece is on the long arm (called the q arm) of chromosome 15. The duplication is thought to contain at least six genes in most people who have the syndrome.[1]

It is thought that changes in one of the genes in the region, called CHRNA7, may cause an increased risk for seizures or behavioral problems.[1][4][6] However, in general it is not known exactly why the extra genetic information on chromosome 15 can cause medical, developmental, and behavioral problems. It is also not known exactly why there can be such a wide range of problems associated with the syndrome, with some people not having any problems at all. It is possible that other genetic or environmental factors influence the problems that each person with the syndrome has.[1]

Diagnosis

The medical, developmental, and behavioral problems caused by 15q13.3 microduplication syndrome are very similar to problems caused by other chromosome disorders or other genetic syndromes. Therefore, when a child has a number of medical, developmental, or behavioral problems, a doctor may suspect that there could be a chromosome disorder and will first order a genetic test called a chromosomal microarray (CMA). This test looks for extra or missing pieces of chromosomes. Most people who are diagnosed with 15q13.3 microduplication syndrome had a CMA completed based on signs such as feeding problems, developmental delay, or behavioral problems.[1]

Treatment

Treatment for 15q13.3 microduplication syndrome typically includes physicaloccupational, and speech therapies. Children with the syndrome may require extra help in school or other therapies to help manage behavioral challenges such as autism. These therapies may help people with the syndrome reach their full potentials.[1]

Other treatments that may be recommended for people with 15q13.3 microduplication syndrome include antiepileptic drugs to treat seizuresMelatonin may be recommended to help children with difficulty sleeping (insomnia) sleep at night.[1]

Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

    • Unique is a source of information and support for families and individuals affected by rare chromosome disorders. Click on the link to view information about 15q13.3 microduplication syndrome.

      In-Depth Information

      • PubMed is a searchable database of medical literature and lists journal articles that discuss 15q13.3 microduplication syndrome. Click on the link to view a sample search on this topic.

        References

        1. 15q13.3 microduplications. Unique. 2013; https://www.rarechromo.org/media/information/Chromosome%2015/15q13.3%20microduplications%20FTNW.pdf.
        2. Xie Y. Is Chromosome 15q13.3 Duplication Involving CHRNA7 Associated with Oral Clefts?. Child Neurology Open. October-December 2015; 2(4):https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5417031/.
        3. Bacino CA. Microduplication syndromes. UpToDate. December 29, 2017; https://www.uptodate.com/contents/microduplication-syndromes#H12818248.
        4. Beal JC. Case Report: Neuronal Migration Disorder Associated With Chromosome 15q13.3 Duplication in a Boy With Autism and Seizures. J Child Neurol. December 2014; 29(12):NP186-188. https://www.ncbi.nlm.nih.gov/pubmed/24282185.
        5. Zhou D, Gochman P, Broadnax DD, Rapoport JL, and Ahn K. 15q13.3 duplication in two patients with childhood-onset schizophrenia. American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics. September 2016; 171(6):777-783. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5069586/.
        6. Bacchelli E, Battaglia A, Cameli C, Lomartire S, Tancredi R, Thomson S, Sutcliffe JS, and Maestrini E. Analysis of CHRNA7 rare variants in autism spectrum disorder susceptibility. American Journal of Medical Genetics. Part A. April 2015; 167A(4):715-723. https://www.ncbi.nlm.nih.gov/pubmed/25655306.

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