Low Fasting Concentrations of Glucagon in Patients with Very Long-Chain Acyl-CoA Dehydrogenase Deficiency.

(1) Background: Deficiencies of mitochondrial fatty acid oxidation (FAO) define a subgroup of inborn errors of metabolism, with medium-chain acyl-CoA dehydrogenase deficiency (MCAD) and very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) being two of the most common. Hypoketotic hypoglycemia is a feared clinical complication and the treatment focuses on avoiding hypoglycemia. In contrast, carnitine uptake deficiency (CUD) is treated as a mild disease without significant effects on FAO. Impaired FAO has experimentally been shown to impair glucagon secretion. Glucagon is an important glucose-mobilizing hormone. If and how glucagon is affected in patients with VLCAD or MCAD remains unknown. (2) Methods: A cross-sectional study was performed with plasma hormone concentrations quantified after four hours of fasting. Patients with VLCAD (n = 10), MCAD (n = 7) and CUD (n = 6) were included. (3) Results: The groups were similar in age, sex, weight, and height. The glucagon and insulin levels were significantly lower in the VLCAD group compared to the CUD group (p < 0.05, respectively). The patients with CUD had glucagon concentrations similar to the normative data. No significant differences were seen in GLP-1, glicentin, glucose, amino acids, or NEFAs. (4) Conclusions: Low fasting concentrations of glucagon are present in patients with VLCAD and cannot be explained by altered stimuli in plasma.

Incidence of Idiopathic Intracranial Hypertension in Individuals With Gonadotropin-Releasing Hormone Analogue Treatment for Gender Dysphoria in Sweden.

This cohort study examines the incidence of idiopathic intracranial hypertension (IHH) among individuals in Sweden undergoing gonadotropin-releasing hormone analogue (GnRHa) treatment for gender dysphoria.

Very long-chain acyl-CoA dehydrogenase deficiency in a Swedish cohort: Clinical symptoms, newborn screening, enzyme activity, and genetics.

Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a recessive disorder of fatty acid beta-oxidation with variable phenotype. Patients may present during the neonatal period with lethal multi-organ failure or during adulthood with a myopathic phenotype. VLCADD is included in the Swedish newborn screening (NBS) program since 2010. The study describes the phenotype and biochemical findings in relation to the genotype, enzyme activity, and screening data in a Swedish cohort of pediatric patients with VLCADD. A total of 22 patients (20 diagnosed via NBS between 2010 and 2019, two diagnosed pre NBS) were included. Parameters analyzed were enzyme activity (palmitoyl CoA oxidation rate); ACADVL genotype; NBS results including Collaborative Laboratory Integrated Reports (CLIR) score; biochemical findings; treatment; clinical outcome. A clinical severity score (CSS) was compiled using treatment interventions and clinical symptoms. A possible correlation between CSS and VLCAD residual enzyme activity and NBS CLIR score was analyzed. The most common ACADVL variant (c.848T>C) was identified in 24/44 alleles. Five novel variants were detected. Clinical manifestations varied from asymptomatic to severe. There was a correlation between CSS, residual enzyme activity, and CLIR scores. Most patients diagnosed via NBS had less severe disease compared to those clinically diagnosed. In conclusion, the identified correlation between the NBS CLIR score, residual enzyme activity, and clinical outcome suggests that information available neonatally may aid in treatment decisions.

Altered mitochondrial metabolism in peripheral blood cells from patients with inborn errors of ß-oxidation.

Inborn errors of mitochondrial fatty acid oxidation (FAO), such as medium-chain acyl-CoA dehydrogenase deficiency (MCAD) and very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) affects cellular function and whole-body metabolism. Carnitine uptake deficiency (CUD) disturbs the transportation of fatty acids into the mitochondria, but when treated is a mild disease without significant effects on FAO. For improved clinical care of VLCAD in particular, estimation of FAO severity could be important. We have investigated whether the oxygen consumption rate (OCR) of peripheral blood mononuclear cells (PBMCs) obtained from patients with MCAD, VLCAD, and CUD can be used to study cellular metabolism in patients with FAO defects and to determine the severity of FAO impairment. PBMCs were isolated from patients with VLCAD (n = 9), MCAD (n = 5-7), and CUD (n = 5). OCR was measured within 6-hours of venous puncture using the Seahorse XFe96. The PBMCs were exposed to glucose alone or with caprylic acid (C8:0) or palmitic acid (C16:0). OCR was significantly lower in cells from patients with ß-oxidation deficiencies (MCAD and VLCAD) compared to CUD at basal conditions. When exposed to C16:0, OCR in VLCAD cells was unchanged, whereas OCR in MCAD cells increased but not to the levels observed in CUD. However, C8:0 did not increase OCR, as would be expected, in VLCAD cells. There was no clear relationship between clinical severity level and OCR. In patients with ß-oxidation deficiencies, changes of mitochondrial respiration in PBMCs are detectable, which indicate that PBMCs have translational potential for studies of ß-oxidation defects. However, further studies are warranted.

Absence of TXNIP in Humans Leads to Lactic Acidosis and Low Serum Methionine Linked to Deficient Respiration on Pyruvate.

Thioredoxin-interacting protein (TXNIP) is an α-arrestin that can bind to and inhibit the antioxidant protein thioredoxin (TXN). TXNIP expression is induced by glucose and promotes ß-cell apoptosis in the pancreas, and deletion of its gene in mouse models protects against diabetes. TXNIP is currently studied as a potential new target for antidiabetic drug therapy. In this study, we describe a family with a mutation in the TXNIP gene leading to nondetectable expression of TXNIP protein. Symptoms of affected family members include lactic acidosis and low serum methionine levels. Using patient-derived TXNIP-deficient fibroblasts and myoblasts, we show that oxidative phosphorylation is impaired in these cells when given glucose and pyruvate but normalized with malate. Isolated mitochondria from these cells appear to have normal respiratory function. The cells also display a transcriptional pattern suggestive of a high basal activation of the Nrf2 transcription factor. We conclude that a complete lack of TXNIP in human is nonlethal and leads to specific metabolic distortions that are, at least in part, linked to a deficient respiration on pyruvate. The results give important insights into the impact of TXNIP in humans and thus help to further advance the development of antidiabetic drugs targeting this protein.

GH Dose Reduction Maintains Normal Prepubertal Height Velocity After Initial Catch-Up Growth in Short Children.

Context: GH responsiveness guides GH dosing during the catch-up growth (CUG) period; however, little is known regarding GH dosing during the prepubertal maintenance treatment period. Objective: To evaluate whether SD score (SDS) channel parallel growth with normal height velocity can be maintained after CUG by reducing the GH dose by 50% in children receiving doses individualized according to estimated GH responsiveness during the catch-up period. Design and Settings: Prepubertal children (n = 98; 72 boys) receiving GH during CUG (GH deficient, n = 33; non-GH deficient, n = 65), were randomized after 2 to 3 years to either a 50% reduced individualized dose (GHRID; n = 27; 20 boys) or unchanged individualized dose (GHUID; n = 38; 27 boys). Another 33 children (25 boys) continued a standard weight-based dose [43 µg/kg/d (GHFIX)]. Main Outcome Measures: The primary endpoint was the proportion of children with ΔheightSDS within ±0.3 at 1 year after GH dose reduction compared with two control groups: GHUID and GHFIX. The hypothesis was that heightSDS could be maintained within ±0.3 with a reduced individualized GH dose. Results: For the intention-to-treat population at 1 year, 85% of the GHRIDgroup maintained ΔheightSDS within ±0.3 vs 41% in the GHUIDgroup (P = 0.0055) and 48% in the GHFIXgroup (P = 0.0047). The ΔIGF-ISDS in the GHRID group was -0.75 ± 1.0 at 3 months (P = 0.003) and -0.72 ± 1.2 at 1 year compared with the GHUID group (0.15 ± 1.2; P = 0.005) and GHFIX group (0.05 ± 1.0; P = 0.02). Conclusions: Channel parallel growth (i.e., normal height velocity) and IGF-ISDS levels within ±2 were maintained after completed CUG using a 50% lower individualized dose than that used during the CUG period.

High DPP-4 Concentrations in Adolescents Are Associated With Low Intact GLP-1.

Context: Dipeptidyl peptidase 4 (DPP-4) metabolizes glucagon-like peptide-1 (GLP-1), and increased DPP4 levels are associated with obesity and visceral adiposity in adults. Objective: Investigating DPP-4 levels in adolescents and their association with (1) circulating intact GLP-1 levels and glucose tolerance; (2) body mass index (BMI); and (3) visceral, subcutaneous, and liver fat compartments. Design: Cross-sectional study, July 2012 to April 2015. Setting: Pediatric obesity clinic, Uppsala University Hospital. Patients and Participants: Children and adolescents with obesity (n = 59) and lean controls (n = 21) aged 8 to 18 years. Main Outcome Measures: BMI SD score, fasting plasma concentrations of DPP-4, total and intact GLP-1, fasting and oral glucose tolerance test (OGTT) concentrations of glucose, and visceral adipose tissue (VAT) and subcutaneous adipose tissue volumes and liver fat fraction. Results: Plasma DPP-4 levels decreased with age in both obese (41 ng/mL per year) and lean subjects (48 ng/mL per year). Plasma DPP-4 levels were higher in males in both the obesity and lean groups. With adjustments for age and sex, plasma DPP-4 level was negatively associated with intact GLP-1 at fasting (ß = -12.3; 95% CI: -22.9, -1.8) and during OGTT (ß = -12.1; 95% CI: -22.5, -1.7). No associations were found between DPP-4 and plasma glucose levels measured at fasting or after a 2-hour OGTT. Plasma DPP-4 level was 19% higher in obese subjects. Among adipose tissue compartments, the strongest association was with VAT (ß = 0.05; 95% CI: -0.02, 0.12). Conclusions: In adolescents, high plasma DPP-4 concentrations were associated with low proportions of intact GLP-1, high BMI, young age, and male sex. The observed associations are compatible with increased metabolism of GLP-1 in childhood obesity.

Most patients with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency develop pathological or subnormal retinal function.

AIM: There have been few studies on long-term electroretinographic findings in patients with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD). This study correlated long-term electroretinographic findings with age, metabolic control and clinical symptoms. METHODS: We examined 12 Swedish patients with LCHADD. Visual acuity testing, fundus examinations, optical coherence tomography and electroretinography were performed. The results were correlated to age, the levels of 3-hydroxyacylcarnitine and acylcarnitine and clinical metabolic control. RESULTS: Blindness or moderate visual impairment was found in two patients. Retinal pigmentation, atrophy and fibrosis were present in 11, seven and one of the patients, respectively, and optical coherence tomography showed retinal thinning in three of the six patients examined. Electroretinography was performed on 11 of the 12 patients. It was pathological, with reduced rod and cone responses, in five patients, subnormal in four and was related to poor clinical metabolic control and severe neonatal symptoms. Repeated electroretinographies revealed reduced function with increasing age. CONCLUSION: More than 80% of the LCHADD patients developed pathological or subnormal retinal function. This was more pronounced in patients with neonatal symptoms, but ameliorated by strict dietary treatment. Annual ophthalmological follow-ups, with electroretinography every second or third year, are recommended.

Decreased GH dose after the catch-up growth period maintains metabolic outcome in short prepubertal children with and without classic GH deficiency.

OBJECTIVE: Few studies have evaluated metabolic outcomes following growth hormone (GH) treatment in short prepubertal children during different periods of growth. Previously, we found that individualized GH dosing in the catch-up period reduced the variation in fasting insulin levels by 34% compared with those receiving a standard GH dose. We hypothesized that the GH dose required to maintain beneficial metabolic effects is lower during the prepubertal growth phase after an earlier catch-up growth period. DESIGN: Short prepubertal children with isolated GH deficiency or idiopathic short stature were randomized to individualized GH treatment (range, 17-100 µg/kg/day) or a standard dose in a preceding 2-year study. After achieving near mid-parental height(SDS) , children receiving an individualized dose were randomized to either a 50% reduced individualized dose (RID, n = 28) or an unchanged individualized dose (UID, n = 37) for 2 years. The dose remained unchanged in 33 children initially randomized to receive a standard dose (FIX, 43 µg/kg/day).We evaluated whether the variations in metabolic parameters measured during maintenance growth diminished in RID compared with UID or FIX. RESULTS: We observed less variation in fasting insulin levels (-50%), insulin sensitivity as assessed by homoeostasis model assessment (-55·1%), lean soft tissue (-27·8%) and bone mineral content (-31·3%) in RID compared with UID (all P < 0·05), but no differences compared with FIX. CONCLUSIONS: Continued reduced individualized GH treatment after the catch-up growth period is safe and reduces hyperinsulinism. Individualized GH dose can be reduced once the desired height(SDS) is achieved to avoid overtreatment in terms of metabolic outcome.

Adenosine kinase deficiency disrupts the methionine cycle and causes hypermethioninemia, encephalopathy, and abnormal liver function.

Four inborn errors of metabolism (IEMs) are known to cause hypermethioninemia by directly interfering with the methionine cycle. Hypermethioninemia is occasionally discovered incidentally, but it is often disregarded as an unspecific finding, particularly if liver disease is involved. In many individuals the hypermethioninemia resolves without further deterioration, but it can also represent an early sign of a severe, progressive neurodevelopmental disorder. Further investigation of unclear hypermethioninemia is therefore important. We studied two siblings affected by severe developmental delay and liver dysfunction. Biochemical analysis revealed increased plasma levels of methionine, S-adenosylmethionine (AdoMet), and S-adenosylhomocysteine (AdoHcy) but normal or mildly elevated homocysteine (Hcy) levels, indicating a block in the methionine cycle. We excluded S-adenosylhomocysteine hydrolase (SAHH) deficiency, which causes a similar biochemical phenotype, by using genetic and biochemical techniques and hypothesized that there was a functional block in the SAHH enzyme as a result of a recessive mutation in a different gene. Using exome sequencing, we identified a homozygous c.902C>A (p.Ala301Glu) missense mutation in the adenosine kinase gene (ADK), the function of which fits perfectly with this hypothesis. Increased urinary adenosine excretion confirmed ADK deficiency in the siblings. Four additional individuals from two unrelated families with a similar presentation were identified and shown to have a homozygous c.653A>C (p.Asp218Ala) and c.38G>A (p.Gly13Glu) mutation, respectively, in the same gene. All three missense mutations were deleterious, as shown by activity measurements on recombinant enzymes. ADK deficiency is a previously undescribed, severe IEM shedding light on a functional link between the methionine cycle and adenosine metabolism.

Growth hormone (GH) dosing during catch-up growth guided by individual responsiveness decreases growth response variability in prepubertal children with GH deficiency or idiopathic short stature.

CONTEXT: Weight-based GH dosing results in a wide variation in growth response in children with GH deficiency (GHD) or idiopathic short stature (ISS). OBJECTIVE: The hypothesis tested was whether individualized GH doses, based on variation in GH responsiveness estimated by a prediction model, reduced variability in growth response around a set height target compared with a standardized weight-based dose. SETTING: A total of 153 short prepubertal children diagnosed with isolated GHD or ISS (n = 43) and at least 1 SD score (SDS) below midparental height SDS (MPH(SDS)) were included in this 2-yr multicenter study. INTERVENTION: The children were randomized to either a standard (43 microg/kg.d) or individualized (17-100 microg/kg.d) GH dose. MAIN OUTCOME MEASURE: We measured the deviation of height(SDS) from individual MPH(SDS) (diffMPH(SDS)). The primary endpoint was the difference in the range of diffMPH(SDS) between the two groups. RESULTS: The diffMPH(SDS) range was reduced by 32% in the individualized-dose group relative to the standard-dose group (P < 0.003), whereas the mean diffMPH(SDS) was equal: -0.42 +/- 0.46 and -0.48 +/- 0.67, respectively. Gain in height(SDS) 0-2 yr was equal for the GH-deficient and ISS groups: 1.31 +/- 0.47 and 1.36 +/- 0.47, respectively, when ISS was classified on the basis of maximum GH peak on the arginine-insulin tolerance test or 24-h profile. CONCLUSION: Individualized GH doses during catch-up growth significantly reduce the proportion of unexpectedly good and poor responders around a predefined individual growth target and result in equal growth responses in children with GHD and ISS.

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. METHODS: Ten children with LCHAD deficiency underwent repeated ophthalmological evaluations including ERG. RESULTS: All 10 children developed chorioretinal pathology. Regardless of age at diagnosis, initiation of treatment and age at examination, inter-individual differences were present. Profound chorioretinal atrophy, severe visual impairment and progressive myopia had developed in two teenagers. Milder chorioretinopathy with or without subnormal visual acuity was present in all other children. ERG was pathological in seven children. The chorioretinopathy often started in the peripapillary or perimacular areas. In one patient, unilateral visual impairment was associated with fibrosis. CONCLUSION: Early diagnosis and adequate therapy might delay but not prevent the progression of retinal complications. Late diagnosis with severe symptoms at diagnosis, neonatal hypoglycaemia and frequent decompensations may increase the progression rate of the chorioretinopathy. LCHAD deficiency, a potentially lethal disease, is sometimes difficult to diagnose. Unusual chorioretinal findings should alert the ophthalmologist to the long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, especially if there is a history of neonatal hypoglycaemia or failure to thrive.