Investigation of genomic instability in paediatric Barrett's oesophagus using laser microdissection on...

To investigate the occurrence of microsatellite instability (MSI) in paediatric Barrett's oesophagus (BE) with the aim of identifying a potential marker for patients at risk for developing dysplasia or adenocarcinoma at a later stage.

Endoscopic oesophageal biopsies from 6 pediatric patients harbouring BE and 6 age-matched controls were retrospectively investigated. After all of the samples were made anonymous, a 5-microm section was cut and stained with toluidine blue. A precise cell was selected and captured using a laser microdissection microscope. Microsatellite analysis was performed on the DNA extracted from the captured cells. Genomic DNA was amplified by polymerase chain reaction using primers for 5 mononucleotide repeats and analysed by GeneMapper software on an ABI 3730. DNA extracted from a formalin-fixed colonic adenocarcinoma known to have MSI was used as a positive control.

The median age of the patients with BE was 9 years. The relevant complaint was long-standing vomiting in 4 cases and history of dysphagia in 3 cases (1 case had both symptoms). All of the cases had a history of reflux oesophagitis with histological confirmation of oesophagitis. Reflux was associated with a hiatus hernia, obesity, and cerebral palsy in each of 3 cases, and with asthma in 2 patients. Histologically, all of the cases showed the presence of specialized intestinal metaplasia containing goblet cells replacing the squamous oesophageal epithelium. None of the cases tested showed any evidence of MSI.

A single molecular marker that would allow recognition of those patients at risk for Barrett's adenocarcinoma has not yet been identified. The absence of MSI in our cases could be due to the need for a longer period of BE before genomic instability develops, or MSI may only arise in a proportion of patients. This does not exclude other genetic alterations, however rare they may be.