11 The risk of incorrect reporting or misinterpretation of genotype results

Abstract

Objective To determine the possibility and likelihood of inaccurate genotype results in CF. Methods Over 500 genotype results were collected at a centre for adult CF care. Genotype results were entered into a database to generate study data. Genotype results were repeated if a.the result was unclear and repeat testing was requested by the genetic testing laboratory, b.the managing clinician had significant concerns regarding genotype/phenotype correlation or c.results held in the database were incomplete, i.e. one single mutation was identified and no second mutation was found, using an older (smaller) panel of probes. Results From over 500 genotypes collected between 1991 and 2014, there were 5 results that were found to be inaccurate/misread on repeat testing. AB was described as having the same mutation as her brother CD, being F508del/F508del. On subsequent testing, he had R117H/unk. F508del was not proven on re-testing. EF had been treated as CF. On repeat testing he was found to be homogygous for R117H. GH was found to be 3454G>C with a typographical error. IJ was identified as unk/unk, and extended testing was unhelpful, however like siblings AB and CD, was found to have a gene abnormality (unspecified) like his brother. PatientInitialSubsequentChange statusABF508del/F508delunk/unkYCDF508del/F508delRII7H/unkYEFR117H/unkR117H/R117HYGHF508del/345G>CF508del/3454G>CNIJunk/unkunk/unkN Conclusion Genotype results may be incorrect or misinterpreted in 1% of patients. Retesting and consultation is important if doubt exists.