Prenatal chromosome microarray: 'The UK experience'. A survey of reporting practices in UK genetic services (2012-2019).

ABSTRACT

BACKGROUND: The value of chromosome microarray (CMA) in the prenatal detection of significant chromosome anomalies is well-established. To guide the introduction of this technique in routine clinical practice, the Joint Committee on Genomics in Medicine developed national UK guidelines for reporting prenatal CMA in 2015. OBJECTIVE: To evaluate the UK experience of utilising prenatal CMA. METHOD: A 36-item survey was distributed to all UK clinical genetics services (n = 23) in March 2019 requesting information pertaining to experience since diagnostic testing commenced and current practice (March 2018 to March 2019). RESULTS: Eighteen UK genetics services currently offer prenatal CMA. A total of 14,554 tests had been performed. A pathogenic copy number variant was identified in 7.8% of tests overall, though the diagnostic rate increased to 8.4% in the final year of the survey. Variants of uncertain significance (VUS) were reported in 0.7% of tests, and 'actionable' incidental findings in 0.12%. CONCLUSION: Diagnostic rate has improved over time, while reporting of VUS has decreased. Reviewing survey responses at a national level highlights variation in testing experience and practice, raising considerations both for future guideline development and implementation of other novel techniques including prenatal whole exome sequencing.