Long-term metabolic follow-up and clinical outcome of 35 patients with maple syrup urine disease

BACKGROUND

Maple syrup urine disease (MSUD) is a rare disease that requires a protein-restricted diet for successful management. Little is known, however, about the psychosocial outcome of MSUD patients. This study investigates the relationship between metabolic and clinical parameters and psychosocial outcomes in a cohort of patients with neonatal-onset MSUD.

METHODS

Data on academic achievement, psychological care, family involvement, and biochemical parameters were collected from the medical records of neonatal MSUD patients treated at Necker Hospital (Paris) between 1964 and 2013.

RESULTS

Thirty-five MSUD patients with a mean age of 16.3 (2.1-49.0) years participated. Metabolic decompensations (plasma leucine >380 μmol/L) were more frequent during the first year of life and after 15 years, mainly due to infection and dietary noncompliance, respectively. Leucine levels increased significantly in adulthood: 61.5% of adults were independent and achieved adequate social and professional integration; 56% needed occasional or sustained psychological or psychiatric care (8/19, with externalizing, mood, emotional, and anxiety disorders being the most common). Patients needing psychiatric care were significantly older [mean and standard deviation (SD) 22.6 (7.7) years] than patients needing only psychological follow-up [mean (SD) 14.3 (8.9) years]. Patients with psychological follow-up experienced the highest lifetime number of decompensations; 45% of families had difficulty coping with the chronic disease. Parental involvement was negatively associated with the number of lifetime decompensations.

CONCLUSION

Adults had increased levels of plasma leucine, consistent with greater chronic toxicity. Psychological care was associated with age and number of decompensations. In addition, parental involvement appeared to be crucial in the management of MSUD patients.

Acute and long-term effects of intracerebroventricular administration of α-ketoisocaproic acid on oxidative stress parameters and cognitive and noncognitive behaviors

Maple Syrup Urine Disease (MSUD) is biochemically characterized by elevated levels of leucine, isoleucine and valine, as well as their corresponding transaminated branched-chain α-keto acids in tissue and biological fluids. Neurological symptoms and cerebral abnormalities, whose mechanisms are still unknown, are typical of this metabolic disorder. In the present study, we evaluated the early effects (1 h after injection) and long-term effects (15 days after injection) of a single intracerebroventricular administration of α-ketoisocaproic acid (KIC) on oxidative stress parameters and cognitive and noncognitive behaviors. Our results showed that KIC induced early and long-term effects; we found an increase in TBARS levels, protein carbonyl content and DNA damage in the hippocampus, striatum and cerebral cortex both one hour and 15 days after KIC administration. Moreover, SOD activity increased in the hippocampus and striatum one hour after injection, whereas after 15 days, SOD activity decreased only in the striatum. On the other hand, KIC significantly decreased CAT activity in the striatum one hour after injection, but 15 days after KIC administration, we found a decrease in CAT activity in the hippocampus and striatum. Finally, we showed that long-term cognitive deficits follow the oxidative damage; KIC induced impaired habituation memory and long-term memory impairment. From the biochemical and behavioral findings, it we presume that KIC provokes oxidative damage, and the persistence of brain oxidative stress is associated with long-term memory impairment and prepulse inhibition.

Psychosocial Issues in Families Affected by Maple Syrup Urine Disease

The primary aim of this study was to ascertain the psychosocial issues faced by families affected by maple syrup urine disease (MSUD). The psychosocial adjustment and quality of life of children with MSUD were also described. Participants included 55 families and their children (ages 5 to 18 years) and teachers. Measures included a MSUD Family Survey, the Behavior Assessment System for Children (BASC) and the Pediatric Quality of Life Inventory (PedsQL). Parents reported via the MSUD Family Survey that the greatest sources of stress were financial and emotional. Many parents reported difficulty interacting with the medical staff and with schools. On the BASC, half of the children fell within the average range in psychosocial adjustment, although there were elevations in scales measuring attention, hyperactivity, and learning problems. On the PedsQL, the mean quality of life scores were closer to children with cancer than to a healthy sample. Despite the emotional and financial burden, parents reported that MSUD has also had a positive influence on their lives, leading to a world-view that is more compassionate and caring.

Social outcome in adults with maple syrup urine disease (MSUD)

BACKGROUND

In MSUD, dietary treatment aims at the protection of the brain from functional disturbances and structural damage by keeping the branched-chain amino acids in plasma permanently in the near-normal range. Unfortunately, delay in effective treatment of the neonatal manifestation and poor long-term metabolic control are common in MSUD patients, leading to impaired cognitive outcome. Some studies have analysed cognitive capacity but only few data are available on social status (educational qualification, interpersonal relationships, lifestyle) in adult patients, which is one measure for the success of treatment.

AIM

In this study we analysed sociodemographic data of 22 adult patients suffering from classic or very severe variant MSUD in comparison with data on an age-matched control collective of the population of Germany.

RESULTS

The analysis revealed low educational and professional levels with a low rate of participation in the labour force by adult MSUD patients. The educational level in patients of migrant origin was lower than the educational qualifications in the native patient group. A large number of patients did not live a normal adult life. Patients could not live autonomously, did not have a steady partnership and had no children.

CONCLUSION

Despite substantial improvement in the treatment of MSUD in recent years, unimpaired outcome of patients with classic or very severe variant MSUD remains a rare finding. Care must be further optimized in order to improve intellectual and, thereby, social outcome. Particular care must be exercised in the treatment of migrant patients who offer special problems due to cultural peculiarities and language difficulties.

Impact of longitudinal plasma leucine levels on the intellectual outcome in patients with classic MSUD

Maple syrup urine disease (MSUD) is an inherited deficiency of branched chain alpha-ketoacid dehydrogenase (BCKDH) activity impairing the degradation of the branched chain amino acids valine, leucine, and isoleucine. Classic MSUD may lead to severe neonatal encephalopathy including coma and impaired cognitive outcome in later life. Early start of dietary treatment and careful metabolic control may improve the outcome of patients with classic MSUD. The aim of this study was to investigate the impact of long-term metabolic control assessed by plasma leucine levels on cognitive outcome in patients with classic MSUD. Plasma leucine levels of 24 patients were obtained retrospectively for the first 6 y of life and yearly medians of mean plasma leucine levels were calculated. At the age of 6 y, IQ tests were performed. Yearly medians of mean plasma leucine levels yielded three homogeneous clusters (low, intermediate, high). Patients of the low cluster showed statistically significant higher IQ scores compared with those of those of intermediate and high clusters. Long-term plasma leucine levels are associated with impaired cognitive outcome in patients with classic MSUD. To achieve the best possible intellectual outcome for affected individuals, we recommend that in infants and preschool children the target range for plasma leucine should not exceed 200 micromol/L.

Maple syrup urine disease-treatment and outcome in patients of Turkish descent in Germany

Maple syrup urine disease (MSUD) is a rare autosomal recessive disorder that causes acute and chronic brain dysfunction because of a neurotoxic effect of the accumulating branched chain amino acids (BCAA) and their corresponding keto acids. Aim of the treatment is a rapid reversal of the neonatal decompensation and a stable long-term metabolic control obtained by a carefully adjusted BCAA-low diet. In optimally treated patients, an unimpaired neurological and intellectual outcome is possible. Ten patients of Turkish origin suffering from MSUD are presently treated in the Metabolic Unit of the University Hospital in Düsseldorf, Germany. All patients show mild intellectual deficits; neurological impairment is rare. This paper aims to define the feasible standard of therapy and the resulting intellectual and psychosocial outcome achievable in MSUD patients of Turkish origin under high standard conditions of medical care for inborn errors of metabolism.

Intrahippocampal administration of the alpha-keto acids accumulating in maple syrup urine disease provokes learning deficits in rats

Learning disability is a common feature of patients affected by maple syrup urine disease (MSUD). However, the pathomechanisms underlying learning deficit in this disorder are poorly known. In the present study, we investigated the effect of acute administration of the alpha-keto acids accumulating in MSUD into the hippocampus on the behavior of rats in the open field and in the inhibitory avoidance tasks. Adult male Wistar rats received intrahippocampal injections of alpha-ketoisocaproic acid (KIC, 8 micromol), alpha-ketoisovaleric acid (KIV, 5 micromol), alpha-keto-beta-methylvaleric acid (KMV, 5 micromol), or NaCl (8 micromol) (controls) immediately after or 10 min before training. Testing session was performed 24 h later. Posttraining administration of the keto acids had no effect on learning in the open-field task. In contrast, pretraining administration of KIV and KMV impaired habituation in the open field. Similarly, pretraining administration of KIC, KIV, and KMV affected rat performance in the inhibitory avoidance task, suggesting disruption of acquisition. The results indicate that the alpha-keto acids accumulating in MSUD induce learning deficits in aversive and nonaversive tasks. We therefore suggest that these findings may be related to the psychomotor delay/mental retardation observed in MSUD, and may indicate the contribution of increased brain concentrations of these organic acids to the pathophysiology of the neurological dysfunction of MSUD patients.

Acute axonal neuropathy in maple syrup urine disease

A 25-year-old woman with maple syrup urine disease (MSUD) developed generalized weakness over 1 week. She had severe leg and moderate arm weakness, areflexia, and distal sensory loss. Plasma branched-chain amino acid concentrations were elevated, reflecting an acute exacerbation of the disease. Electrodiagnostic studies indicated an acute axonal polyneuropathy and sural nerve biopsy revealed acute wallerian degeneration without inflammation. Peripheral neuropathy, although not identified previously as a clinical feature of MSUD, may become more common as chronic dietary restrictions and improved management of the disease allow survival into adulthood.

Intellectual performance of children with maple syrup urine disease

The intellectual performance of 22 children aged 3-16 years with maple syrup urine disease (MSUD) was assessed and compared to a group of early treated phenylketonuria (PKU) children and normal subjects matched by age, sex, nationality, and socio-economic status. All subjects were tested by one examiner only using the age related versions of the non-verbal Snijders-Oomen intelligence test. The mean IQ (+/- SD) score was 74 +/- 14 (range 50-103) in patients with MSUD, 101 +/- 12 (range 87-125) in early treated PKU patients, and 107 +/- 9 (range 90-122) in normal subjects. Intercorrelations indicated that length of time after birth that plasma leucine concentration remained > 1 mmol/l and quality of long-term metabolic control have important influences on IQ.