17q12 microdeletion syndrome, also known as 17q12 deletion syndrome, is a rare chromosomal anomaly caused by the deletion of a small amount of material from a region in the long arm of chromosome 17. It is typified by deletion of the HNF1B gene, resulting in kidney abnormalities and renal cysts and diabetes syndrome. It also has neurocognitive effects, and has been implicated as a genetic factor for autism and schizophrenia. 17q12 microdeletion syndrome is not to be confused with 17q12 microduplication syndrome, caused by the addition of genetic material in the same region from which it is removed in the microdeletion, or 17q21.31 microdeletion syndrome, another name for Koolen–De Vries syndrome. Presentation
17q12 microdeletions have a variable phenotype, ranging from few or no symptoms to severe disability. The condition is thought to be underdiagnosed, and cases with milder phenotypes may not reach clinical attention unless they have an affected child themselves. The most characteristic symptom is renal cysts and diabetes syndrome (RCAD), also known as "type 5 diabetes", which is caused by deletion of the associated HNF1B gene in the region. RCAD is associated with kidney abnormalities and a characteristic form of diabetes that causes atrophy of the pancreas. However, some people with 17q12 microdeletions have normal renal function. RCAD is diagnosed in approximately 40% of people with 17q12 microdeletions, usually prior to age 25, while kidney abnormalities more broadly occur in approximately 85-90%.People with 17q12 microdeletions have a characteristic facial phenotype, albeit a subtle one not usually obvious in daily life.
It is one of the ten most common microdeletions amongst children with idiopathic developmental delay. Microduplication
17q12 microduplication syndrome is far rarer than the corresponding microdeletion, estimated to occur roughly one-fifth as frequently as 17q12 microdeletion syndrome. Due to its rarity and the overlap between their phenotypes, 17q12 microduplications are usually discussed as an adjunct to microdeletions. Like the microdeletion syndrome, the microduplication syndrome has a broad phenotypic range, ranging from asymptomatic to profound disability; intellectual disability is frequently but not always more severe than the microdeletion, while physical health is often better. Epilepsy is a frequent finding. A case of sex reversal has been reported. While autism comorbid with 17q12 microduplication has been reported, it appears far rarer than in the microdeletion. Physical anomalies associated with 17q12 microduplication syndrome include syndactyly, microcephaly, epicanthic folds, and thick eyebrows or a unibrow. The 17q12 microduplication appears to have a low penetrance, as many cases are inherited from asymptomatic parents. See also
Causes of autism
Risk factors of schizophrenia

References


== External links ==