Metabolic Unit from Hospital Clínico Universitario de Santiago de Compostela. Santiago de Compostela. Spain.

MSUD Newborn screening in Galicia and Spain Galicia is a region in the North-West of Spain where extended newborn screening (NBS) with the use of tandem mass spectrometry technology has been well established since 2000. In fact, we have been its pioneers in Spain and one of the first European countries to implement it. Diseases screened by NBS include maple syrup urine disease MSUD which is detected by measuring the whole blood combined leucine-isoleucine concentration and its ratio to other amino acids such as alanine and phenylalanine. MSUD has been recently included in the newborn screening from other Spanish regions, however it is not officially recommended for all the territory.

Our Inherited Metabolic Disease Center in Galicia has been designated as one of the seven National Reference Centers in Spain, and we receive patients from all over the country, Portugal and South America.

Once a neonate is identified, how quickly are they treated?

We have developed a protocol for the steps to follow when a patient is detected by NBS. First the neonate is identified. If the results are very abnormal being suggestive of a severe pathology, our staff from the Metabolic Unit contacts the family by phone and informs them about the significance of the results and what they need to do. Our staff knows perfectly the evolution, prognosis and available treatments for these diseases.

Usually, it is necessary to act very fast when a neonate with MSUD is detected, so we advise the families to come to our Center to manage the patient. Both the Laboratory and the Clinical Unit have an efficient Emergency Attention Service in order to immediately assist these patients.

Prevalence and evolution of patients with MSUD detected by NBS

An estimated prevalence of 1 in 185,000 newborns with MSUD has been found in the world [1]. However, in certain communities there is an over-expression of this entity, such as the Mennonite [1,2] and in our region, Galicia, where the reported incidence is 1 in 52,541 newborns [3]. At this moment we have 7 patients with MSUD detected by NBS and all of them, except 2 with intermediate forms, are classical MSUD.

Those newborns with classical MSUD already exhibited symptoms of intoxication with elevated levels of leucine (> 1500μM) at the moment of detection (usually first seven days of life), although encephalopathy with signs of cerebral edema and coma was only detected in 2 out of 8 patients. One of these 2 patients was detected in 2001 when screening was advised at 5-8 days of life, showing the importance of early NBS. We now screen at Day 3.

None of our patients have required hepatic transplant, and they are all managed with dietary and pharmacologic treatment. During follow-up patients received not only a dietary leucine restriction, according to age and tolerance, but also valine, isoleucine and thiamine (100- 300 mg per day) supplementation. In addition, it is well-established that oxidative stress contributes to brain damage in MSUD, and the use of appropriate antioxidants offers new perspectives for the prevention of the neurological damage in MSUD [4]. Our patients, according to the control and treatment protocol also receive vitamin complex with vitamin A, vitamin E and a frequent intake of selenium. The micronutrient profile is analysed annually providing specific mineral and/or vitamin supplements if deficiencies are detected. We have detected selenium deficiency in several patients.

Metabolic formula is free for the affected families in Spain, and in Galicia its distribution is centralized in the nearest hospital to their residence.

The main goal is to maintain leucine concentrations below 300μmol/L and, in children under 6 years old, to keep this level below 200μmol/L, with isoleucine and valine levels between 200-400μmol/L, controlling the normal range concentrations of glutamine, alanine, tryptophan, tyrosine, methionine and the ratios Leu/Tyr and Leu/Ala.

During an acute intercurrent illness the treatment protocol is carefully managed with a cessation or reduction of the protein intake to 50% for 24h-48h, depending on the severity of the illness, whilst providing a high energy intake with an extra 20% of caloric requirements through carbohydrates, lipids and double dose of carnitine, valine and isoleucine. In case of vomiting or clinical deterioration, an urgent hospital admission for intravenous glucose infusion without branched-chain amino acids (BCAAs) is recommended. The clinical course is subsequently monitored. Currently in Spain, a parenteral amino acid mixture without leucine, valine and isoleucine is available and we find that it brings our patients greater safety.

Cognitive function is assessed in all of our patients by the Psychomotor Development Index (PDI) or the Intellectual Quotient (IQ) giving normal results. One patient with an enzyme activity of 4% (moderate phenotype) and without neonatal encephalopathy developed a mood disorder (based on DSM-IV criteria) which responded favorably to standard antidepressants. We hypothesize that this may be related to higher mean leucine and BCAAs levels in this child as measurements were performed much less frequently than recommended.

We believe that it is very important for achieving optimal metabolic control that the measurement of BCAAs in a dried blood spot sampling (leucine, isoleucine and valine) is performed. This is sent directly by the parents to our laboratory. We recommend that families monitor BCAAs levels once per week, which is usually not practical without a “send-in” filter paper method.

We have recently conducted a study assessing our data from MSUD patients in collaboration with other three Spanish regions [5] with the objective of comparing the evolution between patients detected early by NBS or late. Our study results support that NBS improves prognosis of MSUD patients. Even for those not detected by NBS, an aggressive treatment together with a close monitoring of leucine levels improves neurological evolution.

  1. The inclusion of MSUD in the NBS programs with early sample taking improves the prognosis of these patients.
  2. In order to achieve an optimal metabolic control of MSUD leucine levels should be kept as closest as possible to the normal range (between 100 to 300 μmol/L).
  3. When decompensation is highly suspicious, BCAA measured in a dried blood spot allows us to obtain the sample at the patient’s home and to know in a few hours the results in order to hasten the therapeutic management.
  4. The availability of a parenteral amino acid mixture without leucine, valine and isoleucine brings patients with MSUD a greater safety in their management.


[1] Puffenberger EG.Genetic heritage of the Old Order Mennonites of southeastern Pennsylvania.Am J Med Genet C Semin Med Genet. 2003; 121C:18-31.

[2] Morton DH, Strauss KA, Robinson DL, Puffenberger EG, Kelley RI. Diagnosis and treatment of maple syrup (Galicia cont. on page 14) 14 MSUD NEWSLETTER • SUMMER/FALL 2015 disease: astudy of 36 patients.Pediatrics 2002;109: 999–1008.

[3] Couce ML, Castiñeiras DE, Bóveda MD, Baña A, Cocho JA, Iglesias AJ, Colón C, Alonso-Fernández JR, FragaJM. Evaluation and long-term follow-up of infants with inborn errors of metabolism. Mol Genet Metab 2011;104:470-75.

[4] Sitta A, Ribas GS, Mescka CP, Barschak AG, Wajner M, Vargas CR. Neurological damage in MSUD: the role of oxidative stress. Cell MolNeurobiol 2014; 34(2):157-65.

[5] Couce ML, Ramos F, Bueno MA, Díaz J, Meavilla S, Bóveda MD, Fernández-Marmiesse A, García-Cazorla A. Evolution of maple syrup urine disease in patients diagnosed by newborn screening versus late diagnosis. Eur J Pediatr Neurol 2015;19(6):652-9.


The MSUD Family Support Group is currently funding several research projects and we are proactively looking for researchers interested in developing new treatments or finding a cure for MSUD. Significant funding is necessary if we are to accomplish this goal.
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