1. North East Thames Regional Genetics Service; Great Ormond Street Hospital for Children NHS Foundation Trust; London UK
2. UK NEQAS for Molecular Genetics, Department of Laboratory Medicine; Royal Infirmary of Edinburgh; Edinburgh UK
3. Genetics and Genomic Medicine; UCL Great Ormond Street Institute of Child Health; London UK
4. West Midlands Regional Genetics Laboratory; Birmingham Women's NHS Foundation Trust; Birmingham UK