Transcript MCADD
Pregnancy & Newborn Screening Developments Medium Chain Acyl CoA Dehydrogenase Deficiency (MCADD) What is MCADD • Medium Chain Acyl-CoA Dehydrogenase Deficiency • Caused by the lack of an enzyme (‘catalyst’) required to convert stored fat to energy • Affects 1 in 10,000 babies born in the UK • In Scotland screening should identify 5 – 10 cases a year What is MCADD • Fatty acids are an important energy reserve (fuel) during periods of poor calorie intake, fasting or during infections • Patients with MCADD have a deficiency of an enzyme necessary for the breakdown of medium chain fatty acids • Medium chain fats accumulate and make toxic substances which cause serious symptoms. Why screen for MCADD • Early identification results in early treatment reducing risk of acute life threatening episodes • Early detection of MCADD allows crisis/sudden death to be avoided • Adherence to dietary management - normal life can be expected Complications of MCADD • Because fat fuels cannot be used, these patients quickly use up glucose and may develop hypoglycaemia • High levels of partially broken down fatty acids and low blood glucose concentrations causes the patient to become drowsy, comatosed and eventually stop breathing • Short term effects: seizures, cardiac arrest, coma, sudden death • Long term effects: developmental and behavioural disabilities, failure to thrive, cerebral palsy and attention deficit disorder • 1 in 4 infants die at 1st presentation before diagnosis made Diagnosing MCADD • Tandem Mass Spectrometry (TMS) • Acyl carntine (C8) raised • Diagnosis confirmed by repeat blood test at follow up visit • DNA test for common mutations (Dundee laboratory) • Carriers are not intentionally identified How is MCADD managed? • Scottish National Screening Laboratory notify Regional Metabolic Team (RMT) in Glasgow or Edinburgh • RMT contacts family by telephone to give screening result and follow up plan • RMT informs MCADD Designated Team (MDT)* • Provide MDT and/or GP, HV or midwife with MCADD resource pack • Arrange face-to-face consultation by member of MCADD Designated Team and/or GP, HV or midwife as per local protocol • Arrange follow up visit with MCADD Designated Team within 24 hours or as soon as practically possible *MDT may be same as the RMT for some NHS Boards How is MCADD managed? • • • • • • Fasting should be avoided Parents need to know how to manage a ‘metabolic crisis’ Regular ‘safe’ time between feeds/meals Treat if vomiting/drowsy with glucose polymer feeds Emergency – IV dextrose Refer urgently to clinician who understands condition – metabolic specialist • On going care shared between RMT and MDT How is MCADD managed? MCADD Resource Pack: • • • • MCADD is suspected leaflet Contact details for MCADD Designated Team and the Regional Team A & E information GP information Genetic facts about MCADD • A child that has MCADD has inherited two altered genes, one from each parent, both of whom are carriers • It is thought that between 1 in 40 and 1 in 80 healthy people are carriers and do not have any symptoms • MCADD gene found on chromosome 1 • Most common mutation,985A>G found in 85-90% of those with symptoms, but over 25 other variants found Genetic facts about MCADD • For each pregnancy where both parents are carriers, there is: – 25% chance that the child will be born with MCADD – 50% chance the child will be carrier of the MCADD gene – 25% chance that the child will not be a carrier nor have the disease Additional Management of MCADD • Babies must complete a full immunisation programme • Influenza vaccine is recommended annually • Some children may require a supplement of a vitamin-like substance called carnitine to prevent carnitine deficiency • Anaesthetic procedures require an infusion of dextrose before, during and following procedure Family Issues • Families will require genetic counselling • Older siblings born before newborn screening started will need to be tested – arranged by metabolic clinician • Next child: early testing as well as routine testing