Sudden infant death syndrome (SIDS) is the unexpected death, usually during sleep, of a seemingly healthy baby before the age of one year. Around 300 infants die from SIDS every year in the UK. Despite decades of research it remains unclear exactly why this happens; however a temporary inability of the baby to breathe efficiently is thought to be an important factor.

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calendar-icon 29 March 2018

An internationally recognised research consortium including St George’s, University of London, University College London; and the Mayo Clinic in the USA set out to discover whether a fault in a specific gene affecting muscle function could explain why some infants die.

The gene they examined, SCN4A, codes for a sodium channel protein; this protein is essential for muscle function enabling normal contraction and relaxation. Mutations in this gene are associated with a range of genetic neuromuscular disorders including periodic paralysis and life-threatening pauses in breathing.

The collaboration between the research teams enabled one of the largest genetic SIDS studies to date in which the DNA sequence of the SCN4A gene was assessed in 278 white European SIDS cases and 729 white European controls. The group found that genetic changes in the SCN4A gene from SIDS cases clearly impaired sodium channel function when tested in vitro. In contrast, they did not find any changes in the control group that impaired sodium channel function.

This discovery strongly suggests that a fault in the SCN4A gene may explain why some infants die and that genetic dysfunction of the muscle sodium channel gene is a new, previously unrecognised, risk factor for SIDS. Since patients with the muscle disorders resulting from faults in this gene can have their symptoms treated with available drugs, the research raises a new question as to whether such drugs may have any role in SIDS prevention. Further research is needed to establish how common such genetic changes are and to assess if there is any case for genetic screening.

Co-author Dr Elijah Behr, Reader in Cardiovascular Medicine and Honorary Consultant Cardiologist at St George’s, University of London, said: ‘Up until now genetic heart disease was thought to be the primary genetic contribution to sudden unexplained death in infants. This research has opened up the possibility of previously unsuspected rare and treatable genetic causes.”

This work was the result of an international collaboration with partners at UCL, St George’s,University of London, Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory USA, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, University of Copenhagen, Sheffield Children’s NHS Foundation Trust, University of Bristol and Kings College London. It was published in The Lancet.