Prenatal chromosome microarray: 'The UK experience'. A survey of reporting practices in UK genetic services...

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.

To evaluate the UK experience of utilising prenatal CMA.

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).

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%.

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.