Sep

8q11.23 Duplication

Duplications of the q11.23 region on the long arm of chromosome 8 are commonly associated with various psychological concerns and developmental delays. Psychological concerns may include obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, low frustration tolerance, sleep disturbance, decreased sensitivity to pain, and, most commonly, schizophrenia^1,². Individuals with OCD due to 8q11.23 duplications may have a variety of symptoms including predominant washing, cleaning compulsions, or aggressive intrusive thoughts¹. Additionally, in some cases of schizophrenia, individuals may experience suicidal thoughts or ideations².

Individuals with 8q11.23 duplications may also present with various intellectual and developmental delays. For example, one individual with 8q11.23 duplication was found to be clumsy, have an uncoordinated gate, and speech delay within the first 3 years of life². This same individual was shown to have mild psychomotor delays and memory impairment at 4 years of age². It is common for those with 8q11.23 duplications to present with some extent of intellectual delays, but it is less common for features such as speech delay or autism spectrum disorder to develop².

While less common, 8q11.23 duplications may cause certain facial or bodily features. This includes frontal bossing, short philtrum, high palate, and a single transverse palmar crease¹.

It is thought that these features, especially schizophrenia or intellectual and developmental delays, are related to the duplication of the RB1CC1 gene¹. RB1CC1 is located within the 8q11.23 segment and is frequently expressed in the brain². It functions by regulating several cellular processes including progression, differentiation, senescence, apoptosis, neural migration/spreading, and neurodegeneration². It has
been seen that both complete and partial duplications of RB1CC1 may result in many of the previously described features².

References

¹Maier A, von Zedtwitz K, Maier SJ, et al.(2025). Obsessive-Compulsive symptoms and heterozygous microduplication of the RB1CC1 gene. Biol Psychiatry Glob Open Sci. 5(4):100516.
²Errichiello E, Giorda R, Gambale A, et al. (2021). RB1CC1 duplication and aberrant overexpression in a patient with schizophrenia: further phenotype delineation and proposal of a pathogenetic mechanism. Mol Genet Genomic Med. 9(1): e1561.