Delphine Martin

Recognition and management of fatty acid oxidation defects: A series of 107 patients

In a personal series of 107 patients, we describe clinical presentations, methods of recognition and therapeutic management of inherited fatty acid oxidation (FAO) defects. As a whole, FAO disorders appear very severe: among the 107 patients, only 57 are still living. Including 47 siblings who died early in infancy, in total 97 patients died, of whom 30% died within the first week of life and 69% before 1 year. Twenty-eight patients presented in the neonatal period with sudden death, heart beat disorders, or neurological distress with various metabolic disturbances. Hepatic presentations were observed in 73% of patients (steatosis, hypoketotic hypoglycaemia, hepatomegaly, Reye syndrome). True hepatic failure was rare (10%); cholestasis was observed in one patient with LCHAD deficiency. Cardiac presentations were observed in 51% of patients: 67% patients presented with cardiomyopathy, mostly hypertrophic, and 47% of patients had heart beat disorders with various conduction abnormalities and arrhythmias responsible for collapse, near-miss and sudden unexpected death. All enzymatic blocks affecting FAO except CPT I and MCAD were found associated with cardiac signs. Muscular signs were observed in 51% of patients (of whom 64% had myalgias or paroxysmal myoglobinuria, and 29% had progressive proximal myopathy). Chronic neurologic presentation was rare, except in LCHAD deficiency (retinitis pigmentosa and peripheral neuropathy). Renal presentation (tubulopathy) and transient renal failure were observed in 27% of patients. The diagnosis of FAO disorders is generally based on the plasma acylcarnitine profile determined by FAB-MS/MS from simple blood spots collected on a Guthrie card. Urinary organic acid profile and total and free plasma carnitine can also be very helpful, mostly in acute attacks. If there is no significant disturbance between attacks, the diagnosis is based upon a long-chain fatty acid loading test, fasting test, and in vitro studies of fatty acid oxidation on fresh lymphocytes or cultured fibroblasts. Treatment includes avoiding fasting or catabolism, suppressing lipolysis, and carnitine supplementation. The long-term dietary therapy aims to prevent periods of fasting and restrict long-chain fatty acid intake with supplementation of medium-chain triglycerides. Despite these therapeutic measures, the long-term prognosis remains uncertain.

Arrhythmias and Conduction Defects as Presenting Symptoms of Fatty Acid Oxidation Disorders in Children

BACKGROUND The clinical manifestations of inherited disorders of fatty acid oxidation vary according to the enzymatic defect. They may present as isolated cardiomyopathy, sudden death, progressive skeletal myopathy, or hepatic failure. Arrhythmia is an unusual presenting symptom of fatty acid oxidation deficiencies. METHODS AND RESULTS Over a period of 25 years, 107 patients were diagnosed with an inherited fatty acid oxidation disorder. Arrhythmia was the predominant presenting symptom in 24 cases. These 24 cases included 15 ventricular tachycardias, 4 atrial tachycardias, 4 sinus node dysfunctions with episodes of atrial tachycardia, 6 atrioventricular blocks, and 4 left bundle-branch blocks in newborn infants. Conduction disorders and atrial tachycardias were observed in patients with defects of long-chain fatty acid transport across the inner mitochondrial membrane (carnitine palmitoyl transferase type II deficiency and carnitine acylcarnitine translocase deficiency) and in patients with trifunctional protein deficiency. Ventricular tachycardias were observed in patients with any type of fatty acid oxidation deficiency. Arrhythmias were absent in patients with primary carnitine carrier, carnitine palmitoyl transferase I, and medium chain acyl coenzyme A dehydrogenase deficiencies. CONCLUSIONS The accumulation of arrhythmogenic intermediary metabolites of fatty acids, such as long-chain acylcarnitines, may be responsible for arrhythmias. Inborn errors of fatty acid oxidation should be considered in unexplained sudden death or near-miss in infants and in infants with conduction defects or ventricular tachycardia. Diagnosis can be easily ascertained by an acylcarnitine profile from blood spots on filter paper.

Heterogeneity of persistent hyperinsulinaemic hypoglycaemia. A series of 175 cases.

Abstract. Hyperinsulinism is a heterogeneous disorder characterised by severe hypoglycaemia due to an inappropriate oversecretion of insulin. In a personal series of 175 patients investigated for hyperinsulinaemic hypoglycaemia over the last 20 years, we review clinical presentations, molecular studies and therapeutic management of hyperinsulinism. There were 98 neonatal-onset patients, including 86 permanent hyperinsulinism and 12 transient forms, 68 with infancy-onset and nine with childhood-onset. Hyperammonaemia was found in 12 out of 69 patients tested, 4 neonates and 8 infants. Neonates were clinically more severely affected than infants. Diagnosis of infancy-onset hyperinsulinism was often delayed because of less profound hypoglycaemia and better tolerance to hypoglycaemia. Neonates required higher rates of iv glucose than infants to maintain normal plasma glucose levels (16 mg/kg per min versus 12 mg/kg per min). Only 16% of neonates were diazoxide-sensitive compared to 66% of the infants. Neonates with hyperammonaemia or transient hyperinsulinism were diazoxide-sensitive. Most neonates were pancreatectomised whereas 65% of the infants were treated medically. Among surgically-treated patients, 47% had a focal adenomatous hyperplasia (31 neonates and 13 infants) and 53% a diffuse form of hyperinsulinism (39 neonates and 11 infants). Diazoxide-responsiveness in the focal and diffuse forms did not differ in both neonates and infants; it depended only upon the age of onset of hypoglycaemia. One or two mutations, SUR1 or KIR6.2, were found in 41 of 73 neonates who were investigated and in 13/38 infants using polymerase chain reaction-single strand conformational polymorphism analysis of both genes. Almost all patients with SUR1 (38/41) or KIR6.2 (5/7) mutations were resistant to diazoxide. Ten patients with hyperinsulinism-hyperammonaemia syndrome had a mutation in the glutamate dehydrogenase gene (three neonates and seven infants) after reverse transcriptase-polymerase chain reaction and sequence analysis of cDNA. No mutation was found by polymerase chain reaction-single strand conformational polymorphism in the glucokinase gene. Eight of nine patients with childhood onset hyperinsulinism were treated surgically and histological examination confirmed an adenoma in each case. Conclusion: the clinical severity of hyperinsulinism varies mainly with age at onset of hypoglycaemia. The heterogeneity of hyperinsulinism has major consequences in terms of therapeutic outcome and genetic counselling.

Long-Term Follow-Up of Oral Glucose Tolerance Test-Derived Glucose Tolerance and Insulin Secretion and Insulin Sensitivity Indexes in Subjects With Glucokinase Mutations (MODY2)

OBJECTIVE—We investigated the natural history of glucokinase (GCK)-related maturity-onset diabetes of the young type 2 (MODY2), notably the factors associated with deterioration of hyperglycemia over time. RESEARCH DESIGN AND METHODS—We report an 11-year follow-up of glucose tolerance and indexes of insulin secretion and insulin sensitivity derived from oral glucose tolerance tests in 33 MODY2 subjects. RESULTS—The variation between tests of glucose tolerance (expressed as the area under the glucose curve) was 6.9 ± 3.2% (mean ± SEM), but individual results ranged from −20 to 61%. Deterioration of glucose tolerance between tests was associated with decreased insulin sensitivity, while insulin secretion remained stable. CONCLUSIONS—Glucose tolerance can remain stable over many years in subjects with MODY2 due to the relative stability of the GCK-related β-cell defect. However, the development of insulin resistance may have an important role in the deterioration of the glucose tolerance and in the long-term evolution of the disorder.

Metabolic intermediates in lactic acidosis: compounds, samples and interpretation

SummaryA number of acquired conditions including infections, severe catabolic states, tissue anoxia, severe dehydration and poisoning can give rise to hyperlactacidaemia. All these causes should be ruled out before considering inborn errors of metabolism. Carefully collected samples are necessary if artefacts that results in spuriously increased lactate/pyruvate (L/P) and 3-hydroxybutyrate/acetoacetate (B/A) ratios are to be avoided. When properly performed, 24-h studies of L/P and B/A ratios provide a useful tool in making a diagnosis. A few metabolic profiles when present are specific or highly suggestive of a given disorder. When the L/P ratio is normal or low, pyruvate dehydrogenase (PDH) deficiency is highly probable whatever the lactate concentration, which is often only moderately elevated after meal, may be. When the L/P ratio is very high in association with post-prandial hyperketonaemia and in contrast to a normal or low B/A ratio, pyruvate carboxylase (PC) deficiency andα-ketoglutarate dehydrogenase (KGDH) deficiency are the most likely diagnoses. The distinction between the two disorders relies upon amino acid and organic acid profiles (glutamate andα-ketoglutarate accumulations in KGDH deficiency and hyperammonaemia and hypercitrullinaemia in PC deficiency). When both L/P and B/A ratios are elevated and associated with significant post-prandial hyperketonaemia, respiratory-chain disorders should first be suspected. All other profiles, especially a high L/P ratio without hyperketonaemia, are compatible with respiratory-chain disorders but are not specific; all acquired anoxic conditions should also be ruled out. Clearly, the clinical utility of these profiles needs to be interpreted cautiously in very ill patients in relation to the cardiocirculatory condition and to therapy. Finally, a normal profile, even after stress and loading, does not rule out an inborn error of lactate/pyruvate oxidation.

Recommendations for age‐appropriate education of children and adolescents with diabetes and their parents in the European Union

Education is the keystone of diabetes care, and structured self‐management education is the key to a successful outcome. Existing guidelines provide comprehensive guidance on the various aspects of education and offer general and organizational principles of education, detailed curricula at different ages and stages of diabetes, and recommendations on models, methods, and tools to attain educative objectives. The International Society for Pediatric and Adolescent Diabetes guidelines give the most elaborate and detailed descriptions and recommendations on the practice of education, which other national guidelines address on specific aspects of education and care. The aim of the work package on education developed by Better Control in Paediatric and Adolescent Diabetes in the European Union: Working to Create Centers of Reference (SWEET) project was not to generate new guidelines but to evaluate how the existing guidelines were implemented in some pediatric diabetes reference centers. The SWEET members have completed a questionnaire that elaborates on the many aspects of delivery of education. This survey highlights a profound diversity of practices across centers in Europe, in terms of organization as well as the practices and the content of initial and continuing education. A toolbox is being developed within SWEET to facilitate exchanges on all aspects of education and to establish a process of validation of materials, tools, written structured age‐adjusted programs, and evaluation procedures for the education of children and adolescents with diabetes.

High prevalence of hirsutism and menstrual disorders in obese adolescent girls and adolescent girls with type 1 diabetes mellitus despite different hormonal profiles

OBJECTIVES To compare the pubertal development, the hormonal profiles and the prevalence of hirsutism and menstrual disorders in obese adolescent girls and adolescent girls with type 1 diabetes mellitus (T1DM). METHODS Data were collected from 96 obese adolescent girls and 78 adolescent girls with T1DM at Tanner stage IV or V, whose ages ranged between 11.9 and 17.9 years. RESULTS High prevalence of hirsutism and menstrual disorder was found in the obese adolescent girls (36.5 and 42% respectively) and the adolescent girls with T1DM (21 and 44% respectively). The obese girls were significantly younger at pubarche, thelarche and menarche than the girls with T1DM. Hirsutism in the obese girls and those with T1DM was associated with hyperandrogenaemia and a raised free androgen index (FAI). When the cause of the raised FAI was investigated in both the groups of girls with hirsutism, the raised FAI in the obese girls was due to low serum sex hormone-binding globulin (SHBG) levels. In contrast, the raised FAI of the girls with T1DM and hirsutism was due to hyperandrogenaemia. Menstrual disorders in the T1DM girls were associated also with hyperandrogenaemia unlike obese girls. CONCLUSIONS Hirsutism and menstrual disorders are common in obese adolescent girls and adolescent girls with T1DM. Although hyperandrogenaemia is present in both groups of girls, the androgenic profiles of the two groups differ. The hyperandrogenaemia in the obese girls is primarily due to their decreased serum SHBG levels, whereas the hyperandrogenaemia in the girls with T1DM is due to their increased androgen production.

Changes in insulin therapy regimens over 10 yr in children and adolescents with type 1 diabetes attending diabetes camps

To describe the changes in insulin therapy regimens of children and adolescents with type 1 diabetes over 10 yr and their correlation with hemoglobin A1c (HbA1c).

Genetic hypoglycaemia in infancy and childhood: Pathophysiology and diagnosis

Glucose, like oxygen, is of essential and fundamental importance for brain metabo- lism. The major source of brain glucose is the blood supply and thus a severe encephalopathy will ensue when the glucose content of blood becomes de—cient. A prompt diagnosis is essential and must be achieved safely with an appropriate test. This requires knowledge of the homeostatic mechanisms that maintain the blood glucose concentration between the relatively narrow range of 2.5 and 7.5 mmol/L whether the child is eating or fasting. Within the last decade, many new insights and facts have expanded our knowledge considerably in elucidating the causes and mechanisms of genetic hypoglycaemias. This brief review outlines certain aspects of the regulation of glucose homeostasis and focuses on the causes of genetic hypogly- caemias, in which signi—cant advances have been made recently. DEFINITION After the —rst 72 h of life (term babies) or the —rst week (pre-term babies), hypogly- caemia is generally de—ned as a plasma or capillary whole-blood glucose concentra- tion less than 2.5 mmol/L (Walker 1994). Although it is highly controversial (Cornblath et al 1990; Volpe 1995), there is a growing consensus that in neonates levels above 2.5 mmol/L are desirable. Moreover, and most importantly, these lower limits are probably exceeded when concomitant insults that increase cerebral demand for glucose (like hypoxaemia and ischaemia) accompany hypoglycaemia.

In vivo stable isotope studies in three patients affected with mitochondrial fatty acid oxidation disorders: Limited diagnostic use of 1-13C fatty acid breath test using bolus technique

Abstract The in vivo oxidation of fatty acids (FA) of different chain length was investigated in three patients with documented mitochondrial FA oxidation disorders: one patient with mild multiple acyl-CoA dehydrogenase deficiency (MADM), one with medium chain acyl-CoA dehydrogenase deficiency (MCAD), and one with carnitine palmitoyltransferase I deficiency (CPT I). Breath tests were performed after oral administration of 1-13C butyric, 1-13C octanoic, and 1-13C palmitic acids. 13C/12C ratio in the expired oxidative end product CO2 was measured. The cumulative 13C elimination was calculated and expressed as a percentage of the administered dose. In the MADM patient the influence of carnitine therapy (or deprivation) on the utilization of 1-13C palmitic acid was also examined. In the MCAD and CPT I patients, the 1-13C butyric, 1-13C octanoic and 1-13C palmitic acids in vivo oxidation were similar to five healthy controls. In the MADM patient, the oxidation of 1-13C butyric and 1-13C octanoic acids were normal, whereas the metabolism of 1-13C palmitic acid ranged from 33% to 66% of controls. In this patient the serum carnitine level decreased from 60 to 27 μmol/l without carnitine supplementation. Clinically there was mild hypotonia. 1-13C palmitic acid oxidation compared to controls was 50%. After 2 further weeks of carnitine deprivation the serum carnitine was 10–15 μmol/l. Clinically he was very hypotonic and had a large liver. 1-13C Palmitic acid oxidation was 33%. After 6 weeks of readministration of carnitine (l-carnitine 100 mg/kg/day p.o.) the serum carnitine was 60 μmol/l and the patient was in good clinical condition. 1-13C palmitic acid oxidation was 66% compared to controls. Our study implies that this simple fatty acid breath test is not of diagnostic use for detection of enzymatic defects in FA oxidation disorders. The carnitine dependent 1-13C palmitic acid oxidation indicates that this test might be of some value in cases with primary or secondary carnitine deficiencies.