Proximal 18q-

Proximal 18q- is a rare genetic condition caused by a deletion of genetic material within one of the two copies of chromosome 18. This deletion involves the proximal (near the centromere) section of the long arm of chromosome 18 somewhere between 18q11.2 (18.9 Mb) to 18q21.1 (43.8 Mb). Exact breakpoints vary.

Proximal 18q- causes a range of medical and developmental concerns. There is significant variation in severity due to the variation in breakpoints reported. Current research is focused on establishing genotype-phenotype correlations to enable predictive genotyping.^{[citation needed]}

A group of individuals with similar deletions within this region have been described (Cody et al., 2007): The medical and developmental problems are described below.

Clubfoot has been reported in some individuals. Although it is not a common finding, cryptorchidism has been reported in some boys.

Feedings difficulties and problems with temperature regulation have been reported in some newborns with proximal 18q-.

Recurrent otitis media is frequently associated with proximal 18q- and, in some cases, may cause conductive hearing loss. This may be resolved with the placement of PE tubes.

Many individuals with proximal 18q- have strabismus and/or refractive errors.

Gastrointestinal anomalies are not common in people with proximal 18q-, though there has been at least one individual reported that required g-tube feedings.