Jan Alm

Activating glucokinase (GCK) Mutations as a cause of medically responsive congenital hyperinsulinism: prevalence in children and characterisation of a novel GCK mutation

OBJECTIVE Activating glucokinase (GCK) mutations are a rarely reported cause of congenital hyperinsulinism (CHI), but the prevalence of GCK mutations is not known. METHODS From a pooled cohort of 201 non-syndromic children with CHI from three European referral centres (Denmark, n=141; Norway, n=26; UK, n=34), 108 children had no K(ATP)-channel (ABCC8/KCNJ11) gene abnormalities and were screened for GCK mutations. Novel GCK mutations were kinetically characterised. RESULTS In five patients, four heterozygous GCK mutations (S64Y, T65I, W99R and A456V) were identified, out of which S64Y was novel. Two of the mutations arose de novo, three were dominantly inherited. All the five patients were medically responsive. In the combined Danish and Norwegian cohort, the prevalence of GCK-CHI was estimated to be 1.2% (2/167, 95% confidence interval (CI) 0-2.8%) of all the CHI patients. In the three centre combined cohort of 72 medically responsive children without K(ATP)-channel mutations, the prevalence estimate was 6.9% (5/72, 95% CI 1.1-12.8%). All activating GCK mutations mapped to the allosteric activator site. The novel S64Y mutation resulted in an increased affinity for the substrate glucose (S(0.5) 1.49+/-0.08 and 7.39+/-0.05 mmol/l in mutant and wild-type proteins respectively), extrapolating to a relative activity index of approximately 22 compared with the wild type. CONCLUSION In the largest study performed to date on GCK in children with CHI, GCK mutations were found only in medically responsive children who were negative for ABCC8 and KCNJ11 mutations. The estimated prevalence (approximately 7%) suggests that screening for activating GCK mutations is warranted in those patients.

3-hydroxydicarboxylic aciduria—a fatty acid oxidation defect with severe prognosis

We describe five patients with a suspected defect in the beta-oxidation of fatty acids characterized by a massive excretion of 3-hydroxydicarboxylic acids in the urine and accumulation of 3-hydroxy fatty acids in serum during acute illness. Long-chain and medium-chain acyl-coenzyme A dehydrogenases in fibroblasts were normal in all patients. Four of them died of cardiomyopathy and liver insufficiency at 3 to 14 months of age. Two of the patients had elder siblings who had died unexpectedly in early infancy. These patients differ from previously described patients with beta-oxidation defects.

Family conditions and dietary control in phenylketonuria

SummaryObjectiveThis investigation is an attempt to describe coping with phenylketonuria (PKU) in order to understand some aspects underlying good compliance.MethodsThe coping concept was applied to PKU in two questionnaires. Self- and parental ratings were combined with assessments of phenylalanine levels and the severity of the disease. All Swedish patients with PKU born in 1980–91, a total of 53 children and youths with their parents, were invited to participate in the study and 41 (77%) of them did so.ResultsThe patients turned out to have good compliance with the diet. The main result was that patients with separated or divorced parents were more likely to have higher phenylalanine levels and this association was not diminished by adjustment for the potential confounding factors.ConclusionPatients’ need for support must be judged individually according to different family conditions.

Response to Treatment in Patients with Partial Androgen Insensitivity due to Mutations in the DNA-Binding Domain of the Androgen Receptor

The androgen insensitivity syndrome is a disorder caused by deficient function of the androgen receptor, characterized by varying degrees of undermasculinization in karyotypic males. We have identified four mutations in the androgen receptor gene, in the region encoding the DNA-binding domain of the protein. Two mutations, R607X and R615G, were found in patients with complete insensitivity to androgens, whereas the other two, S578T and A596T, were found in patients with partial insensitivity. The functional consequences of the three missense mutations were assayed in vitro after transient expression of the receptors in COS cells. All mutants showed normal androgen binding but abnormal abilities to stimulate transcription of an androgen-responsive reporter gene. R615G abolished transactivation whereas S578T and A596T were partially malfunctional. The function of A596T, but not of S578T, was normalized at high androgen concentrations in vitro, reflecting the in vivo situation. Thus, patients with specific mutations in the DNA-binding domain of the androgen receptor may benefit from androgen treatment.

Ocular characteristics in 10 children with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency: a cross-sectional study with long-term follow-up

Purpose:  To present long‐term ocular complications and electroretinographic (ERG) findings in children with long‐chain 3‐hydroxyacyl‐CoA dehydrogenase (LCHAD) deficiency – a life‐threatening metabolic disease – and the relation to age at diagnosis, treatment and other clinical parameters.

Rapid Genetic Analysis in Congenital Hyperinsulinism

Backgound: In severe, medically unresponsive congenital hyperinsulinism (CHI), the histological differentiation of focal versus diffuse disease is vital, since the surgical management is completely different. Genetic analysis may help in the differential diagnosis, as focal CHI is associated with a paternal germline ABCC8 or KCNJ11 mutation and a focal loss of maternal chromosome 11p15, whereas a maternal mutation, or homozygous/compound heterozygous ABCC8 and KCNJ11 mutations predict diffuse-type disease. However, genotyping usually takes too long to be helpful in the absence of a founder mutation. Methods: In 4 patients, a rapid genetic analysis of the ABBC8 and KCNJ11 genes was performed within 2 weeks on request prior to the decision of pancreatic surgery. Results: Two patients had no mutations, rendering the genetic analysis non-informative. Peroperative multiple biopsies showed diffuse disease. One patient had a paternal KCNJ11 mutation and focal disease confirmed by positron emission tomography scan and biopsies. One patient had a de novo heterozygous ABBC8 mutation and unexplained diffuse disease confirmed by positron emission tomography scan and biopsies. Conclusion: A rapid analysis of the entire ABBC8 and KCNJ11 genes should not stand alone in the preoperative assessment of patients with CHI, except for the case of maternal, or homozygous/compound heterozygous disease-causing mutations.

Growth in Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency.

UNLABELLED Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency is an inborn error of fatty acid metabolism that affects the degradation of long chain fatty acids and causes insufficient energy production and accumulation of toxic intermediates. The treatment consists of a diet low in fat, with supplementation of medium-chain triglycerides that bypass the metabolic block. In addition, frequent feeds and extra carbohydrates are given during febrile illnesses to reduce lipolysis. Hence, this diet differs from the general dietary recommendations for growing children. Furthermore, the Swedish dietary instructions for fat intake in LCHAD deficiency are given in grams, which differ from most guidelines that recommend fat intake as percentage shares of total caloric intake. AIMS To assess growth in patients with LCHAD deficiency, in relation to dietary treatment and to evaluate if overweight/obesity is more common than in the normal population. RESULTS The growth velocity showed acceleration after diagnosis and the start of treatment, followed by a period of stable or decelerated growth. The majority of the patients developed overweight to a greater extent than children without LCHAD deficiency. Several patients also went through a phase of obesity. Data on final height (FH) showed that three out of five patients had grown according to their genetic potential. CONCLUSIONS Regular and frequent follow-up and careful monitoring of weight are essential to avoid the development of overweight and obesity. The Swedish dietary instructions defining fat intake in total grams per day may be an alternative approach to achieve a moderate total caloric intake.

The Adolescent Adjustment Profile (AAP) in comparisons of patients with obesity, phenylketonuria or neurobehavioural disorders

Psychosocial development in children with chronic disease is a key issue in paediatrics. This study investigated whether psychosocial adjustment could be reliably assessed with the 42-item Adolescent Adjustment Profile (AAP) instrument. The study mainly focused on adjustment-to-obesity measurement, although it compared three patient groups with chronic conditions. All phenylketonuria (PKU) patients in Sweden between ages 9 and 18 and their parents and teachers were invited to participate. Patients with neurobehavioural syndromes and obesity were age- and gender-matched with PKU patients. Healthy children constituted a reference group. Psychosocial adjustment was measured using the AAP, which is a multi-informant questionnaire that contains four domains. Information concerning parents’ socio-economic and civil status was requested separately. Respondents to the three questionnaires judged the PKU patients to be normal in all four domains. Patients with neurobehavioural syndromes demonstrated less competence and the most problems compared with the other three groups. According to the self-rating, the parent rating and the teacher rating questionnaires, obese patients had internalizing problems. The parent rating and the teacher rating questionnaire scored obese patients as having a lower work capacity than the reference group. Compared with the reference group, not only families with obese children but also families with children with neurobehavioural syndromes had significantly higher divorce rates. Obese patients were also investigated with the Strength and Difficulties Questionnaire (SDQ), another instrument that enables comparison between two measures of adjustment. The AAP had good psychometric properties; it was judged a useful instrument in research on adolescents with chronic diseases.

The Kuvan® Adult Maternal Paediatric European Registry (KAMPER) Multinational Observational Study: Baseline and 1-Year Data in Phenylketonuria Patients Responsive to Sapropterin

INTRODUCTION Sapropterin dihydrochloride (Kuvan(®)), a synthetic 6R-diastereoisomer of tetrahydrobiopterin (BH4), is approved in Europe for the treatment of patients aged ≥4 years with hyperphenylalaninaemia (HPA) due to BH4-responsive phenylalanine hydroxylase (PAH) deficiency, in conjunction with a phenylalanine-restricted diet, and also for the treatment of patients with BH4 deficiency. AIMS/METHODS KAMPER is an ongoing, observational, multicentre registry with the primary objective of providing information over 15 years on long-term safety of sapropterin dihydrochloride treatment in patients with HPA. Here we report initial data on characteristics from patients recruited by the time of the third interim analysis and results at 1 year. RESULTS Overall, 325 patients from 55 sites in seven European countries were included in the analysis: 296 (91.1%) patients with PAH deficiency (median [Q1, Q3] age, 10.3 [7.2, 15.0] years) and 29 (8.9%) with BH4 deficiency (12.8 [6.6, 18.9] years). Fifty-nine patients (18.2%) were aged ≥18 years; 4 patients were pregnant. No elderly patients (aged ≥65 years) or patients with renal or hepatic insufficiency were enroled in the study. Twelve-month data were available for 164 patients with PAH deficiency and 16 with BH4 deficiency. No new safety concerns were identified as of May 2013. CONCLUSIONS Initial data from KAMPER show that sapropterin dihydrochloride has a favourable safety profile. Registry data collected over time will provide insight into the management and outcomes of patients with PAH deficiency and BH4 deficiency, including long-term safety, impact on growth and neurocognitive outcomes and the effect of sapropterin dihydrochloride treatment on populations of special interest.

Acute liver failure in a child with Epstein-Barr virus infection and undiagnosed glycerol kinase deficiency, mimicking hemophagocytic lymphohistiocytosis.

Glycerol kinase deficiency (GKD, MIM 307030) is an X-linked disorder caused by impaired ability to metabolize glycerol resulting in elevated levels of glycerol in blood and urine (1). Glycerol kinase catalyzes the phosphorylation of glycerol to glycerol-3-phosphate, an important intermediate in both lipid and carbohydrate metabolism. Glycerol kinase deficiency can be found as an isolated enzyme deficiency or as part of an Xp21 contiguous gene syndrome resulting in a so-called complex form involving NR0B1 (DAX1, the locus associated with adrenal hypoplasia congenita) and the Duchenne muscular dystrophy gene. Isolated GKD may in some cases be present without symptoms; however, in other cases children with isolated GKD may present with vomiting, metabolic acidosis, ketotic hypoglycemia, lethargy, and unconsciousness. These crises can be associated with infections or strenuous physical activity (2). The patients have high concentrations of glycerol in blood and urine (3). Most laboratories determine triglyceride concentration by measuring glycerol after hydrolysis of triglycerides and make the assumption that the glycerol concentration is equal to the triglyceride concentration. This can lead to misinterpretation of the laboratory results and consequently a high level of free glycerol (before hydrolysis) in the case of GKD