Expanding the phenotypic spectrum of Chromosome 16p13.11 microduplication: A multicentric analysis of 206 patients.

INTRODUCTION: Recurrent chromosome 16p13.11 microduplication has been characterised in the literature as a cause of developmental delay, learning difficulties and behavioural abnormalities. It is a neurosusceptibility locus and has incomplete penetrance and variable expression. Other clinical features, such as cardiac abnormalities have also been reported. The duplicated region contains the MYH11 gene, which encodes the protein myosin-11 and is a component of the myosin heavy chain in smooth muscle. Recent literature has suggested 16p13.11 microduplication as one of the possible risk factors for thoracic aortic aneurysms and dissection (TAAD). Therefore, we studied the detailed phenotype of cases of chromosome 16p13.11 microduplication from seven centres in the United Kingdom (UK) to expand the phenotype, focusing on the cardiac abnormalities. METHODS: All individuals with a chromosome 16p13.11 microduplication seen in Clinical Genetics prior to June 2017 in 6 centres (prior to 2018 in the seventh centre) were identified through the regional genetics laboratory databases. A Microsoft Excel® proforma was created and clinical data was collected retrospectively from clinical genetics databases from the seven genetics services in the UK. The data was collated and analysed collectively. RESULTS: The majority of the individuals presented with (72%) developmental delay and (62%) behavioural abnormalities, in keeping with the published literature. 27% had some dysmorphic features, 14% had visual impairment and 8% had congenital cardiac abnormalities. Echocardiograms were performed in 50% of patients, and only 3.8% patients had aortic dilatation and no one had aortic dissection. 9.7% of patients were found to have a second genetic/chromosomal diagnosis, especially where there were additional phenotypic features. CONCLUSION: 16p13.11 microduplication is a neurosusceptibility locus and is associated with variable expression. It may be helpful to refer children with 16p13.11 microduplication for a cardiac review for congenital cardiac abnormalities and also for ophthalmological assessment. Further prospective studies with cardiac assessments are recommended in this cohort of patients to determine whether ongoing aortic surveillance is indicated. Guidelines about the frequency of surveillance are indicated, especially in individuals with normal cardiac findings. We also highlight the importance of considering a second diagnosis if the phenotype is inconsistent with that reported.

Rapid exome sequencing: revolutionises the management of acutely unwell neonates.

Diagnosing acutely unwell infants with a potential genetic diagnosis can be challenging for healthcare professionals. Evidence suggests that up to 13% of critically unwell infants on the neonatal intensive care unit (NICU) have an underlying molecular diagnosis and when identified directly affects treatment decisions in 83%. On 1st October 2019, the National Health Service England (NHSE) launched a nationally commissioned service so that rapid whole-exome sequencing can be offered to critically unwell babies and children with a likely monogenic disorder who are admitted to NICU and paediatric intensive care unit (PICU). We present 7 cases from two neonatal units in the West Midlands (UK), where rapid exome sequencing has revealed a genetic diagnosis. Early genetic diagnosis in this cohort has influenced management in all (100%) cases, and in 57% (4 in 7 cases), it has helped in the decision to reorientate care. In some cases, early diagnosis has reduced the need for invasive and unnecessary investigations and avoided the need for post-mortem investigations. The genetic diagnosis has helped in counselling the families regarding the recurrence risk for future pregnancies. In some cases, this has provided parents with the reassurance of a low recurrence. In others, it has resulted in the offer of prenatal diagnosis or assisted conception technologies. What is Known: • Rapid whole-exome sequencing was commissioned in the UK in October 2019. • It is available for critically unwell babies with a likely monogenic aetiology. What is New: • It helps management planning for rare genetic disorders and future pregnancies counselling. • It can reduce the need for invasive investigations and overall intensive care costs.