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 in a newborn infant

Maple Syrup Urine Disease (MSUD) is a severe metabolic disorder secondary to an enzyme defect in the catabolic pathway of the branched chain amino acids: leucine, isoleucine and valine. Accumulation of these amino acids and derived from them alpha-keto-acids leads to encephalopathy and progressive degeneration of the nervous system in undiagnosed and hence untreated patients. Early diagnosis and elimination diet prevent complications and therefore create a possibility of both normal intellectual and physical progress. In consequence, in a few countries MSUD has been added to newborn screening programmes to create opportunity for early diagnosis especially in newborn infants before clinical symptoms are present. In the study the authors present a case report of a newborn infant with MSUD along with the current knowledge on MSUD diagnosis and treatment.     

Heterozygous liver transplantation for maple syrup urine disease: First European reported case

MSUD is an autosomal recessive metabolic disorder that results from a defect in the BCKDH enzyme. This enzyme is essential for the second step in the metabolism of the branched‐chain amino acids, leucine, isoleucine, and valine. Patients with MSUD are subject to severe, irreversible neurologic injury unless closely managed with a specialized metabolic formula and a diet restricted in leucine throughout their lifetime. During times of illness, patients with MSUD can suffer from severe metabolic derangement, acute cerebral edema, and untimely death. Deceased donor liver transplant restores the ability to metabolize branched‐chain amino acids, even on an unrestricted diet, and prevents metabolic derangements during times of illness. We report a successful case of living donor (parental) transplant for a child with MSUD. The donor was the child's father. This approach has been controversial as parents of children with MSUD are obligate heterozygotes for the condition and have diminished levels of BCKDH activity. If effective, living‐related donor transplant provides a promising alternative for deceased donor liver transplant, which often requires a prolonged waiting period and may not be feasible in areas with limited medical resources.     

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.     

Living donor liver transplantation in maple syrup urine disease – Case series and world's youngest domino liver donor and recipient

MSUD occurs due to deficiency of enzyme BCKAD required for metabolism of leucine, isoleucine, and valine leading to the accumulation of these and their ketoacids causing acute metabolic decompensation manifesting as encephalopathy or sudden death. The patient requires special protein‐restricted diet to survive. As this enzyme is expressed in liver, liver transplantation has been successfully performed as a cure. We report two patients of MSUD who underwent LDLT while their livers were used as a domino graft for other biliary cirrhotic patients. A 22‐month‐old male child diagnosed as a case of classic MSUD underwent LDLT from an altruistic aunt as donor following which his serum leucine levels normalized on an unrestricted protein diet. His liver was used as a domino graft. A 38‐month‐old female child with diagnosed MSUD underwent LDLT from a swap donor, and her liver was used as a domino graft. Her DQ improved post‐transplant. LDLT from non‐heterozygous donors is a cure for classical MSUD. Their livers can be used as domino grafts for non‐MSUD cases.     

Diurnal changes in plasma amino acids in maple syrup urine disease

Protein turnover is a cyclic process with a net loss of protein in the (catabolic) fasted state and a net gain in the (anabolic) fed state. In maple syrup urine disease (MSUD) the early block of degradation of the branched-chain amino acids (BCAA) brings about the opportunity for evaluation of the diurnal variation in net protein anabolism and catabolism by studying cyclic changes in the plasma concentrations of BCAA. The alterations in plasma BCAA in a 3-y-old boy with classical MSUD were studied in the fed and fasted state over a period of 19 months. For each amino acid a total of 34 data pairs was calculated. The plasma concentrations of the BCAA leucine, valine and isoleucine were constantly higher in the fasted than in the fed state. Plasma concentrations of alloisoleucine, being a non-protein amino acid, did not participate in cyclic changes. In contrast, the essential amino acid pair tyrosine and phenylalanine increased after meals. The fasting concentration of alanine increased after feeding, while glycine did not change significantly. Healthy subjects show a decrease in all amino acids in the fasted (mild catabolic) state and an increase in the fed state. These findings in MSUD suggest a net decrease in non-BCAA as result of a greater rate of amino acid oxidation rate than of protein breakdown and a net entry of BCAA into plasma in the fasted state due to the specific metabolic block. Such changes in amino acid plasma pools have to be taken into account during monitoring of treatment and especially when in vivo leucine oxidation is assessed.     

Management of a case of maple syrup urine disease--the use of gluco-insulinotherapy

We report here the treatment and poor outcome of a case of Maple Syrup Urine Disease with late diagnosis and retrieval (2 and 5 months, respectively). As the proband had quite high levels of plasmatic leucine (1956 micromol/L for a normal upper limit of 77), we started immediately with a gluco-insulin therapy to produce anabolism in the infant. When leucine has fallen to 275.3 micromol/L, we instituted feeding with branched chain amino acid-free protein and high energy from carbohydrates. After reviewing briefly the clinical, biochemical and therapeutic aspects of this disorder, we comment on the great difficulties of making early diagnosis and of obtaining the specific dietetic formulas to Maple Syrup Urine Disease, in Brazil.     

新生儿枫糖尿症二例报告并文献复习

目的 探讨新生儿枫糖尿症的临床特点及诊治经验,以提高认识,更好地预防和治疗该病.方法 报道新生儿枫糖尿症2例,并结合国内近15年来已报道的15例进行文献复习.结果 新生儿枫糖尿症的报道有增多趋势.17例发病年龄3 h～8 d,均有喂养困难,7例家族中有类似患儿,14例出现神经系统表现,8例伴特殊气味,13例血中支链氨基酸明显增高,6例利用串联质谱检测,12例尿中支链氨基酸及其代谢产物排泄增加,5例利用尿气相色谱-质谱分析,10例MRI/CT发现异常信号,12例死亡或放弃治疗,1例并发脑瘫,4例经特殊配方奶粉治疗者病情有不同程度好转.结论 新生儿枫糖尿症(maple syrup urine disease,MSUD)早期常出现喂养困难、反应差、嗜睡等非特异性症状,临床需要注意有无特殊气味和神经系统症状,疑诊者应及时进行血、尿氨基酸检测以便早期诊断,MRI(DWI)特异性水肿改变信号也有助于诊断,诊断后应立即干预治疗,同时应加强家长的配合,从而改善其预后.     

3-Methylglutaconic and 3-methylglutaric aciduria in a patient with suspected 3-methylglutaconyl-CoA hydratase deficiency

A girl suffering from marked muscular hypotonia, severe statomotor and mental retardation, bilateral optic atrophy with chorioretinal degeneration, convulsions and a moderate compensated metabolic acidosis is described. Screening for metabolic disorders revealed massive 3-methylglutaconic with 3-methylglutaric aciduria leading to the tentative diagnosis of 3-methylglutaconyl-CoA hydratase deficiency. Metabolite excretion was correlated with variation of leucine intake. 3-methyl-3-hydroxyglutaryl-CoA lyase activity in cultured fibroblasts was normal. The suspected metabolic defect was not demonstrable in cultured skin fibroblasts, however.Abbreviation MSUD Maple syrup urine disease     

A case of classical maple syrup urine disease that was successfully managed by living donor liver transplantation

Classical MSUD is often fatal without appropriate medical interventions because of metabolic crisis. There are numerous reports suggesting the therapeutic potential of deceased donor liver transplantation for MSUD. However, the usefulness of LDLT for MSUD is unknown. We report a case of classical MSUD, which was successfully managed by LDLT from the patient's father at 1 year of age. Abnormal brain findings, which were cured with effective treatment, gradually disappeared after LDLT. The patient then developed normally. Findings from this case suggest the importance of LDLT for maintaining low leucine levels and subsequent normal neurological development. Although LDLT involves a modest surgical insult, LDLT with a related donor achieves acceptable leucine levels for life.     

Outcome of early and long-term management of classical maple syrup urine disease

The outcome of 8,400 treatment days in the lives of four patients with classical maple syrup urine disease (MSUD) (present ages: 1 3/12, 5 7/12, and 8 11/12 years) are described. Each diagnosis was made by clinical signs rather than by newborn screening. Acute-phase treatment beginning on the 11th day of life comprised peritoneal dialysis, intravenous lipid, and early intestinal alimentation. Mean age at discharge from hospital was 29 days. There were 16 readmissions to the hospital for the group (89 days, 1.05% treatment days) without any serious neurologic symptoms. The mean level of plasma leucine for the group (for levels below 1 mM) during treatment was 0.42 mM (normal for age range, 0.077 +/- 0.021 mM [mean +/- SD]). Plasma leucine exceeded 1 mM during 1.02% of treatment days (representing 8.6% of 1,042 measurements. Mean levels of plasma valine and isoleucine were 60% and 70% of the plasma leucine value for the group. Tolerance for dietary leucine did not exceed 620 mg/day in any patient. Somatic growth was normal and the mean current IQ/development quotient (DQ) score is 101 (range 89 to 117); the three oldest patients attend regular schools. A characteristic EEG pattern resembling the teeth of a comb was observed in three patients during the acute phase in the newborn period but not during long-term treatment. These results were obtained in an ambulatory program with home visiting.     

Exchange transfusion in acute episodes of maple syrup urine disease

Two neonates with maple syrup urine disease were treated by exchange transfusion. Within 15 h blood leucine and KICA concentrations were lowered from 2.6 mM to 1.1 mM using 570 to 620 ml blood per kg body weight. The other branched-chain amino acid/keto acid pairs fell to normal. During exchange transfusion the patient's nitrogen balance seems to be negative. Further exchange transfusion was useless. More importantly the patient should be forced into an anabolic state by high caloric supply or insulin plus glucose treatment. More KICA than leucine was eliminated, however, KICA blood levels remained slightly higher than that of leucine indicating different leucine/KICA equilibria in extravascular compartments than in blood. In a given time interval exchange transfusion was more effective than peritoneal dialysis, probably due to a lack of an additional (peritoneal) membrane. Renal excretion of branched-chain amino and keto acids was very inefficient. The allegedly most toxic metabolite, KICA, had the lowest renal clearance of the branched-chain keto acids.Abbreviations BCAA's branched-chain alpha-amino acids - BCKA's branched-chain alpha-keto acids - KICA alpha-keto-isocaproic acid - KIVA alpha-keto-isovaleric acid - MEVA alpha-keto--methyl-n-valeric acid - MSUD maple syrup urine disease - HICA alpha-hydroxy-isocaproic acid - HIVA alpha-hydroxy-isovaleric acid - HMVA alpha-hydroxy--methyl-n-valeric acid With support of the Landesamt für Forschung des Ministeriums für Wissenschaft und Forschung des Landes Nordrhein-Westfalen. U.L. was supported by Deutsche Forschungsgemeinschaft, Bad Godesberg, G.F.R. (La 201 and SFB 33).     

Continuous arteriovenous hemofiltration. Management in case of neonatal leucinosis]

BACKGROUND. Neonates with classic maple syrup urine disease (MSUD) undergo rapid neurological deterioration by the end of the first week of life. Exchange transfusion and peritoneal dialysis are the usual emergency treatment. Continuous arteriovenous hemofiltration (CAVHF) appears to be safe and more rapidly effective. CASE REPORT. Martin was born at the 37th week from a normal pregnancy. Abnormal movements of legs and lethargy appeared on the 7th day of life. Progressive brain dysfunction with coma led to intubation on the 13th day. A diagnosis of MSUD was immediately made and CAVHF was initiated and continued for 19 hours. The plasma leucine, valine and isoleucine levels fell from 2,248 to 275, 640 to 91 and 298 to 13 mumol/l, respectively. Neurologic improvement was dramatic, except for moderate hypertonia which lasted for the 2 following days. CONCLUSION. CAVHF is an appropriate treatment for very young patients with inborn errors of metabolism. It appears safer and more rapidly effective for eliminating branched-chain amino acids than other techniques, such as peritoneal dialysis with or without exchange transfusions. It also permits more rapid introduction of the specific diet.     

Recall rate and positive predictive value of MSUD screening is not influenced by hydroxyproline

Maple syrup urine disease (MSUD) is an autosomal recessive inherited disorder caused by the deficiency of the branched-chain 2-oxo acid dehydrogenase (BCOA-DH) complex. The worldwide incidence is approximately 1 in 185,000. MSUD is integrated in many “expanded” newborn screening (NBS) programs that use electrospray ionization tandem mass spectrometry (ESI-MS/MS). Elevated leucine, isoleucine, and alloisoleucine in the dried blood samples (DBS) of newborns are diagnostic parameters. However, with the applied method, it is not possible to distinguish the amino acids from each other, and also not from the other isobaric amino acid, hydroxyproline. While the branched chain amino acids (BCAA) leucine, isoleucine, and alloisoleucine are no diagnostic problem, because they are all elevated in MSUD patients, and, rather, increase the diagnostic sensitivity and specificity, hydroxyproline may cause false-positive screening results. Hydroxyproline is elevated in the benign familial condition hyperhydroxyprolinemia, which needs no medical intervention. The detection of cases with hyperhydroxyprolinemia have formerly been reported from screening programs that used thin-layer chromatography for phenylketonuria (PKU) screening, and, recently, two more cases have been reported, detected by ESI-MS/MS-based NBS. However, the detection of non-diseases is a heavy burden for screening programs and should be avoided if possible. With optimal settings for the quantitation of BCAAs and interpretation rules, elevated hydroxyproline should not cause false-positive screening results.     

Identification of two novel BCKDHA mutations in a Chinese patient with maple syrup urine disease

Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder affecting branched-chain amino acids. Mutations in the BCKDHA, BCKDHB, and DBT gene impair the branched-chain alpha-ketoacid dehydrogenase (BCKD) complex, resulting in the accumulation of branched-chain amino acids and branched-chain alpha-ketoacid in tissues and plasma. This leads to mental and physical retardation, feeding problems, and a maple syrup odor in the urine. In this study, we describe the clinical and biochemical manifestations of a sporadic mutation in a neonate with classic MSUD. Analysis of the BCKDHA gene revealed a compound heterozygous mutation consisting of two novel missense mutations (p.L103P and p.R265P). Viewing the protein with PyMOL indicated that the p.L103P and p.R265P mutations were, respectively, located in the helical region and core domains of the BCKD's Ela component. The p.L103P mutation affected the hydrophobic cores and is predicted to shorten the helix; the p.R265P mutation can predictably affect the cofactor binding site by ligating the associated manganese ion. In conclusion, we identified two novel missense mutations in the BCKDHA gene in a Chinese patient with MSUD.     

Plasma homocysteine levels and folate status in children with sickle cell anemia.

PURPOSE: A sensitive inverse relationship between plasma homocysteine concentration and folate status has been demonstrated. Although children with sickle cell anemia (SCA) are at potential risk for folate deficiency, plasma homocysteine levels have not been reported in such patients. Therefore, a study was designed to assess plasma homocysteine levels as a marker of folate status. DESIGN: Plasma homocysteine concentrations were measured in 120 children with SCA (102 in steady state and 18 during an acute complication) who had never received supplemental folic acid. Folate status was directly assessed in 34 of these patients. RESULTS: Plasma homocysteine levels in the patients with SCA and control subjects were similar. The mean value +/- 1 SD was 5.8+/-2.5 micromol/L (range, 1.6 to 14.1 micromol/L) in the patients with SCA and 6.1+/-2.7 micromol/L (range, 1.7 to 15.3 micromol/L) in 73 pediatric control subjects. In a subpopulation of the study group (34 children), simultaneous serum folate, red cell folate, and total homocysteine concentrations were also measured. Their serum folate and red cell folate concentrations were normal: 12.4+/-10.0 nmol/L (range, 1 to 42 nmol/L) and 604+/-374.7 nmol/L (range, 205 to 1741 nmol/L), respectively. There was no correlation of plasma homocysteine concentration with various clinical or laboratory measures or with red cell folate concentration. CONCLUSION: Folate stores in children with SCA not receiving folic acid supplements are adequate despite an underlying hemolytic anemia.     

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.     

Two novel mutations in the BCKDHB gene that cause maple syrup urine disease

Background

Maple syrup urine disease (MSUD) is a rare metabolic disorder of autosomal recessive inheritance caused by decreased activity of branched-chain α-ketoacid dehydrogenase complex (BCKD). Mutations in the three genes (BCKDHA, BCKDHB and DBT) are associated with MSUD. Here, we describe the presenting symptoms, clinical course and gene mutation analysis of a Chinese boy with MSUD.

Significance of low or normal serum gamma glutamyl transferase level in infants with idiopathic neonatal hepatitis

INTRODUCTION: We evaluated the significance of low/normal serum gamma glutamyl transferase (GGT) level in infants with idiopathic neonatal hepatitis (INH). MATERIALS AND METHODS: A retrospective review of the hospital records of 103 infants less than 3 months of age who were diagnosed with INH between August 1991 and November 2000 was performed. Variables including age at which jaundice was noticed, age at presentation, perinatal risk factors, family history of liver disease, parental consanguinity, initial ultrasound scan, liver biopsy, laboratory values at the first visit, the peak levels of total bilirubin, aspartate aminotransferase (AST), GGT and alkaline phosphatase (ALP) in the first 3 months of follow-up and interval for normalisation of serum bilirubin and AST were compared between infants presenting with low/normal GGT (100 U/L). RESULTS AND DISCUSSION: Infants with low/normal GGT levels presented earlier (median 36.5 days versus 44 days; p=0.016) and had significantly higher bilirubin and AST levels at presentation (bilirubin 167.5 micromol/L versus 133 micromol/L; p<0.005 and AST 187.5 U/L versus 106 U/L; p<0.001) and at peak levels (bilirubin 170 micromol/L versus 146 micromol/L; p=0.024 and AST 210.5 U/L versus 129 U/L; p=0.001). A significant correlation was also found between GGT levels and serum albumin levels (p=0.004). Patients with low/normal GGT levels were more likely to have giant cell hepatitis on histology (p=0.015). There was no difference in time taken to recovery. CONCLUSION: Low/normal levels of GGT in INH infants may be a predictor of more severe but recoverable disease.     

Serum carnitine and nutritional status in children treated with continuous ambulatory peritoneal dialysis

The serum carnitine (total carnitine), total protein, amino acid, and triglyceride levels were determined in children on continuous ambulatory peritoneal dialysis (CAPD). Compared with levels in controls, serum carnitine levels were significantly decreased in patients on CAPD for more than 4 months, while those of patients on CAPD for 1-3 months were not decreased. Patients on CAPD for more than 4 months also showed lower serum total protein levels than in normal controls. The mean triglyceride levels in patients on CAPD for both 1-3 months and more than 4 months were higher than those in normal controls. Among the amino acids, the serum levels of tryptophan, isoleucine, leucine, tyrosine, valine, serine, and asparagine were significantly lower in patients treated with CAPD than in normal controls, whereas the levels of other amino acids were either increased or not changed. Isoleucine and leucine levels showed a strong correlation with serum carnitine. Our data suggest that malnutrition plays a role in the decrease of serum carnitine levels in patients receiving CAPD.