Anita MacDonald, Consultant Dietitian in Inherited Metabolic Disorders, Birmingham Children’s Hospital, UK

The treatment of maple syrup urine disease (MSUD) necessitates a life-long diet. It aims to reduce intake of the branch chain amino acids while maintaining normal growth and nutritional status, and minimising metabolic decompensation. The anxiety and pressures experienced by patients and their families in adhering to dietary management has received limited study.  The primary aim of this report is to highlight the hurdles that need to be overcome in gaining dietary adherence in MSUD at various ages.

In non-MSUD amino acids disorders treated by diet (e.g. PKU), it is known that blood control of the ‘offending’ amino acid deteriorates with age, especially from around 10 years of age. Although data is more limited in MSUD, evidence would suggest a similar pattern.  Two European MSUD studies reported on adolescents and adult patients who maintained average leucine concentrations higher than the usual treatment range [1, 2. Therefore, it is clear that maintaining strict dietary adherence throughout older life is challenging.

The burden of the disorder and dietary management
The need to adhere every day to strict dietary management is relentless. Treatment is not only about a rigorous dietary regimen, but an endless sequence of administering medical food, home blood tests, emergency procedures, and numerous visits to hospital to see professionals, and this experience is shared by the entire family.  Children may have physical or behavioral feeding difficulties or have limited appetites, and may require constant coercion to take their medical food three to four times daily, which is exhausting for parents.  It is likely to have disruptive effects on the family lifestyle, limit time spent on non-MSUD children [3 , and participation in normal activities such as holidays may be affected. Any accompanying physical or neurodevelopmental disability will create additional challenges. In addition, it is not unusual to have more than one child with MSUD thereby increasing the family workload. In PKU, it was reported that the median time burden associated with management was 527h/year (1 h and 24 min/day) for parents and 175h/year (30 min/day) for adult patients [4. This time is likely to be higher in MSUD.

The patient’s family characteristics
Overall outcome in children depends on parental ability, their discipline, motivation, organization skills, and overall coping ability to continually apply and supervise the dietary regimens. Emotional stress has been reported in 78.4% of MSUD parents 3, and differences in parenting styles may be a source of marital conflict [5.  It has been shown in other conditions 6 that feeling emotionally depleted can compromise parent’s ability to respond to acute illness, and this may be analogous for MSUD.  Family circumstance has the potential to either support or derail adherence to dietary treatment. Households headed by one parent have increased in some countries and low family cohesion and divorce has been shown to have a negative impact on adherence in similar conditions 7. Family disengagement and criticism may be associated with poor adherence in children.  The patient responsibility
As children mature, they are expected to take more responsibility for their diet therapy, and gain more practical and theoretical knowledge so they can lead independent adult lives. This may be particularly challenging for patients with low education ability [5. In particular in MSUD, poor planning, limited organizational skills and poor attention may affect the ability to self-manage their diet outside the home.
In teenagers, some adherence issues surround the need to be accepted by peers and the ‘need to fit in’. They may lack awareness about the effects poor adherence has on some aspects of treatment. Also the diet is seen to complicate social relationships when it makes their condition visible. Teenagers may be less willing to take medical formula in front of others. Negative school experiences have been reported in MSUD 3.

Cultural and religious influences
MSUD is more frequent in populations with a high level of consanguinity, and is particularly prevalent in Muslim communities living in western countries but originating from South Asia and the Middle East. Structural and practical constraints include living in poor housing with limited cooking facilities, large sized families, illiteracy and/or poor language skills; the latter is a major barrier to understanding and accessing basic information about the dietary treatments, which affects their ability to adhere to treatment.

Adherence and information sources
Parents encounter an overwhelming amount of unrestricted and unchecked information from websites, Facebook, Twitter and other sources. MSUD specific information is sparse.*  Equally, patient associations are well established for PKU, but in European countries due to the infrequent incidence of MSUD, family support is less available. Furthermore, families may receive care from a non metabolic-specialist health professional care team who may lack the necessary experience to support and enable the family to deliver the optimum treatment, which may lead to conflict between parents, patients and clinician.

Adherence with medical food
Although medical food is an essential part of treatment, due to its taste adherence is a major issue [3, 5, 8. The development of MSUD specific medical foods has always lagged behind that of the more common disorder, PKU, as international demand is more limited. Consequently the range and flavors available for MSUD medical foods is limited, which may add to dietary non- adherence. Fortunately newer, innovative products are now available which may improve this situation [8].

Financial aspects
Although internationally there is a wide range of special low protein foods available, many governments expect families to purchase them, creating a high annual financial burden [4]. Additionally the cost burden of transportation to clinics and blood testing affect the ability to adhere to diet.

In MSUD, dietary adherence is challenging and affected by many complex interrelated factors. The production of international web based educational tools is likely to be significant in supporting patients and caregivers.  There is much to be learnt by community studies observing day to day issues in patient management in order to improve practical advice and support in the future. Can you include a bit of practical advice?

  1. Schönberger S, Schweiger B, Schwahn B, Schwarz M, Wendel U. Dysmyelination in the brain of adolescents and young adults with maple syrup urine disease. Mol Genet Metab. 2004, 82: 69-75.
  2. le Roux C, Murphy E, Hallam P, Lilburn M, Orlowska D, Lee P. Neuropsychometric outcome predictors for adults with maple syrup urine disease. J Inherit Metab Dis. 2006, 29: 201-2.
  3. Packman W, Henderson SL, Mehta I, Ronen R, Danner D, Chesterman B, Packman S. Psychosocial issues in families affected by maple syrup urine disease.  J Genet Couns. 2007, 16: 799-809.
  4. Ipsiroglu OS, Herle M, Spoula E, Möslinger D, Wimmer B, Burgard P, Bode H,Stöckler-Ipsiroglu S. Transcultural pediatrics: compliance and outcome of phenylketonuria patients from families with an immigration background. Wien Klin Wochenschr. 2005 117(15-16): 541-7.
  5. Packman W, Mehta I, Rafie S, Mehta J, Naldi M, Mooney KH. Young adults with MSUD and their transition to adulthood: psychosocial issues. J Genet Couns. 2012, 21: 692-703.
  6. Bartlett SJ, Krishnan JA, Riekert KA, Butz AM, Malveaux FJ, Rand CS. Maternal depressive symptoms and adherence to therapy in inner-city children with asthma. Pediatrics. 2004, 113: 229-37.
  7. Olsson GM, Montgomery SM, Alm J. Family conditions and dietary control in phenylketonuria. J Inherit Metab Dis. 2007, 30: 708-15.
  8. Hallam P, Lilburn M, Lee PJ. A new protein substitute for adolescents and adults with maple syrup urine disease (MSUD). J Inherit Metab Dis. 2005, 8: h665-72.

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