The prevalence of this condition is unknown. It has been characterized in fewer than 100 patients. 

The 16p13.11 microduplication syndrome is caused by a genetic swapping event between two highly similar DNA sequences at position p13.11 of chromosome 16. The duplications can appear de novo (new, and not inherited from either parent) or can be inherited. Patients only need to inherit the mutation from one parent for disease manifestation (also known as autosomal dominant inheritance pattern). Carriers of the 16p13.11 duplication may have mild symptoms or may be completely normal. 

The duplicated region of chr16p13.11 encompasses approximately 15 genes. It is suggested that the gene copy number, aka the dosage of these genes, is essential for normal development. A complementary syndrome, where the exact region (16p13.11) is deleted increases people’s susceptibility to neurocognitive diseases. Therefore, too many or too few gene copies are both disruptive to brain development. 

The structure of Chromosome 16. Red box labels chr16p13.11, the site of microduplications.

In general, children with 16p13.11 microduplication are healthy at birth. However, up to ~80% of children have behavioral and emotional disorders such as attention deficit hyperactivity disorder (ADHD), language impairment, global developmental delay, hand polydactyly (extra finger), intellectual disability, or joint hyper-flexibility. Some patients may also present aggressive behaviors, abnormal brain sizes, autism spectrum disorder (ASD), anxiety disorder, distinct facial features, congenital heart defects, and vertebral anomalies.

Genetic testing can be performed. Genomic testing methods such as chromosomal microarray (CMA) or targeted duplication analysis (Fluorescence in situ hybridization, FISH, or quantitative PCR) to detect recurrent duplications in the affected individual can help uncover the 16p13.11 microduplication. 

Even though there is no treatment available, a diagnosis of behavioral impairments such as Autism or intellectual disability can be important to provide children with early and tailored access to educational and behavioral therapy.  

Patients who are generally in good health should have a normal lifespan. Some adults with 16p13.11 microduplication syndrome are reported to develop adult-onset cardiovascular disorder including thoracic aortic aneurysm dissection (TAAD). However, this was reported only in a limited number of patients. 

16p13.11 microduplication syndrome （GARD). (2011). Retrieved June 24, 2020, from https://rarediseases.info.nih.gov/diseases/13392/16p1311-microduplication-syndrome

Allach El Khattabi L, Heide S, Caberg JH, et al. 16p13.11 microduplication in 45 new patients: refined clinical significance and genotype-phenotype correlations. J Med Genet. 2020;57(5):301‐307. doi:10.1136/jmedgenet-2018-105389

Hannes, F. D., Sharp, A. J., Mefford, H. C., de Ravel, T., Ruivenkamp, C. A., Breuning, M. H., Fryns, J. P. et al. Recurrent reciprocal deletions and duplications of 16p13.11: the deletion is a risk factor for MR/MCA while the duplication may be a rare benign variant. J. Med. Genet. 46, 223–232 (2008).

Ramalingam, A., Zhou, X., Fiedler, S. et al. 16p13.11 duplication is a risk factor for a wide spectrum of neuropsychiatric disorders. J Hum Genet 56, 541–544 (2011). https://doi.org/10.1038/jhg.2011.42

Rarechromo.org. (n.d.). 16p13.11 microduplications. Retrieved May 20, 2020 from

https://www.rarechromo.org/media/information/Chromosome%2016/16p13.11%20microduplications%20FTNW.pdf

Ullmann, R., Turner, G., Kirchhoff, M., Chen, W., Tonge, B, Rosenberg, C. et al. Array CGH identifies reciprocal 16p13.1 duplications and deletions that predispose to autism and/or mental retardation. Hum. Mutat. 28, 674–682 (2007).