Differences in faecal microbiome composition between adult patients with UCD and PKU and healthy control subjects.

Urea cycle disorders (UCDs) are a group of rare inherited metabolic diseases causing hyperammonemic encephalopathy. Despite intensive dietary and pharmacological therapy, outcome is poor in a subset of UCD patients. Reducing ammonia production by changing faecal microbiome in UCD is an attractive treatment approach. We compared faecal microbiome composition of 10 UCD patients, 10 healthy control subjects and 10 phenylketonuria (PKU) patients. PKU patients on a low protein diet were included to differentiate between the effect of a low protein diet and the UCD itself on microbial composition. Participants were asked to collect a faecal sample and to fill out a 24 h dietary journal. DNA was extracted from faecal material, taxonomy was assigned and microbiome data was analyzed, with a focus on microbiota involved in ammonia metabolism.In this study we show an altered faecal microbiome in UCD patients, different from both PKU and healthy controls. UCD patients on dietary and pharmacological treatment had a less diverse faecal microbiome, and the faecal microbiome of PKU patients on a protein restricted diet with amino acid supplementation showed reduced richness compared to healthy adults without a specific diet. The differences in the microbiome composition of UCD patients compared to healthy controls were in part related to lactulose use. Other genomic process encodings involved in ammonia metabolism, did not seem to differ. Since manipulation of the microbiome is possible, this could be a potential treatment modality. We propose as a first next step, to study the impact of these faecal microbiome alterations on metabolic stability. TAKE HOME MESSAGE: The faecal microbiome of UCD patients was less diverse compared to PKU patients and even more compared to healthy controls.

Erythropoietic protoporphyria: time to prodrome, the warning signal to exit sun exposure without pain-a patient-reported outcome efficacy measure.

PURPOSE: Patients with erythropoietic protoporphyria (EPP), a severe painful photodermatosis, experience prodromal sensations when exposed to sunlight, which are the "warning signals" to exit the sun, as prolonged exposure causes an excruciatingly painful phototoxic attack. The unique prodromal cutaneous sensations are reversible and differ from the severe burning pain attack lasting 2-7 days. Previously, afamelanotide treatment was studied using time to pain or time outside as primary outcome measures. Since patients have an ingrained fear of sunlight, these measures did not capture the full treatment effect. We retrospectively characterized and evaluated time to prodrome (TTP) as a safer, patient-reported outcome (PRO) measure in afamelanotide-treated patients. METHODS: Structured interviews recorded TTP before and during afamelanotide treatment in retrospective US and Dutch cohort studies. RESULTS: Thirty-one US and 58 Dutch EPP patients participated. Before afamelanotide treatment, 54.8% US and 39.7% Dutch patients reported TTP onset <10 minutes in direct sunlight. In both studies, patients' TTP's were significantly longer during afamelanotide treatment (p < 0.0001). All US patients' TTP increased; no TTP was <10 minutes. Among Dutch patients 81% improved; only 10.3% reported TTPs < 10 minutes. CONCLUSION: EPP patients reported substantial improvements in TTP during afamelanotide treatment. TTP could provide a safer, PRO-based efficacy endpoint for assessing future EPP treatments.

High protein prescription in methylmalonic and propionic acidemia patients and its negative association with long-term outcome.

BACKGROUND AND OBJECTIVE: Methylmalonic acidemia (MMA) and propionic acidemia (PA) are inborn errors of metabolism. While survival of MMA and PA patients has improved in recent decades, long-term outcome is still unsatisfactory. A protein restricted diet is the mainstay for treatment. Additional amino acid mixtures (AAM) can be prescribed if natural protein is insufficient. It is unknown if dietary treatment can have an impact on outcome. DESIGN: We performed a nationwide retrospective cohort study and evaluated both longitudinal dietary treatment and clinical course of Dutch MMA and PA patients. Protein prescription was compared to the recommended daily allowances (RDA); the safe level of protein intake as provided by the World Health Organization. The association of longitudinal dietary treatment with long-term outcome was evaluated. RESULTS: The cohort included 76 patients with a median retrospective follow-up period of 15 years (min-max: 0-48 years) and a total of 1063 patient years on a protein restricted diet. Natural protein prescription exceeded the RDA in 37% (470/1287) of all prescriptions and due to AAM prescription, the total protein prescription exceeded RDA in 84% (1070/1277). Higher protein prescriptions were associated with adverse outcomes in severely affected patients. In PA early onset patients a higher natural protein prescription was associated with more frequent AMD. In MMA vitamin B12 unresponsive patients, both a higher total protein prescription and AAM protein prescription were associated with more mitochondrial complications. A higher AAM protein prescription was associated with an increased frequency of cognitive impairment in the entire. CONCLUSION: Protein intake in excess of recommendations is frequent and is associated with poor outcome.

Diagnostic and therapeutic strategies for porphyrias.

Porphyrias are rare metabolic disorders. Lack of awareness and knowledge about the clinical features of porphyrias results in diagnostic and therapeutic delays for many patients. Delays in diagnosing and treating porphyrias can result in severe, progressive morbidity (and mortality) and psychological distress for patients. This review discusses the pathophysiology, diagnosis, treatment, and follow-up of the most prevalent porphyrias: acute intermittent porphyria, porphyria cutanea tarda, and erythropoietic protoporphyria.

The natural history of classic galactosemia: lessons from the GalNet registry.

BACKGROUND: Classic galactosemia is a rare inborn error of carbohydrate metabolism, caused by a severe deficiency of the enzyme galactose-1-phosphate uridylyltransferase (GALT). A galactose-restricted diet has proven to be very effective to treat the neonatal life-threatening manifestations and has been the cornerstone of treatment for this severe disease. However, burdensome complications occur despite a lifelong diet. For rare diseases, a patient disease specific registry is fundamental to monitor the lifespan pathology and to evaluate the safety and efficacy of potential therapies. In 2014, the international Galactosemias Network (GalNet) developed a web-based patient registry for this disease, the GalNet Registry. The aim was to delineate the natural history of classic galactosemia based on a large dataset of patients. METHODS: Observational data derived from 15 countries and 32 centers including 509 patients were acquired between December 2014 and July 2018. RESULTS: Most affected patients experienced neonatal manifestations (79.8%) and despite following a diet developed brain impairments (85.0%), primary ovarian insufficiency (79.7%) and a diminished bone mineral density (26.5%). Newborn screening, age at onset of dietary treatment, strictness of the galactose-restricted diet, p.Gln188Arg mutation and GALT enzyme activity influenced the clinical picture. Detection by newborn screening and commencement of diet in the first week of life were associated with a more favorable outcome. A homozygous p.Gln188Arg mutation, GALT enzyme activity of ≤ 1% and strict galactose restriction were associated with a less favorable outcome. CONCLUSION: This study describes the natural history of classic galactosemia based on the hitherto largest data set.

Fibroblast growth factor 21 as a biomarker for long-term complications in organic acidemias.

BACKGROUND: There is increasing evidence that long-term complications in organic acidemias are caused by impaired mitochondrial metabolism. Currently, there is no specific biomarker to monitor mitochondrial dysfunction in organic acidemias. Serum fibroblast growth factor 21 (FGF-21) is a biomarker for mitochondrial disease and could be a candidate to monitor mitochondrial function in the deleterious course of disease. METHODS: Data of 17 patients with classical organic acidemias (11 propionic acidemia (PA), four methylmalonic acidemia (MMA) and two isovaleric acidemia (IVA) patients) were included. The clinical course was evaluated; metabolic decompensations and long-term complications were correlated with plasma FGF-21 levels. Cardiomyopathy, prolonged QT interval, renal failure, and optic neuropathy were defined as long-term complications. RESULTS: Patients ages ranged from 16 months up to 32 years. Serious long-term complications occurred in eight patients (five PA and three MMA patients). In MMA and PA patients plasma FGF-21 levels during stable metabolic periods were significantly higher in patients with long-term complications (Mdn = 2556.0 pg/ml) compared to patients without (Mdn = 287.0 pg/ml). A median plasma FGF-21 level above 1500 pg/ml during a stable metabolic period, measured before the occurrence of long-term complications, had a positive predictive value of 0.83 and a negative predictive value of 1.00 on long-term complications in MMA and PA patients. CONCLUSION: This study demonstrates the potential role of FGF-21 as a biomarker for long-term complications in classical organic acidemias, attributed to mitochondrial dysfunction.

Osteoporosis in patients with erythropoietic protoporphyria.

BACKGROUND: Erythropoietic protoporphyria (EPP) is a rare metabolic disease with painful photosensitivity due to protoporphyrin IX accumulation. OBJECTIVES: To evaluate bone mineral density (BMD) and known osteoporosis risk factors in patients with EPP. METHODS: Patients with EPP attending the Erasmus MC outpatient clinic who had undergone BMD measurements were included. Plasma 25 hydroxy (OH) vitamin D, alkaline phosphatase, parathyroid hormone and total protoporphyrin IX levels were measured; information on lifestyle, sunlight exposure and a bone-relevant physical exercise index [Bone Physical Activity Questionnaire (BPAQ) score] was obtained via questionnaires. BMD scores and the prevalence of osteopenia and osteoporosis in the EPP population were compared with a reference population. RESULTS: Forty-four patients with EPP (23 female, 21 male; mean age 37·6 years) were included. The mean SDs of the T-scores were -1·12 for the lumbar spine and -0·82 for the femoral neck (both P < 0·001). Osteopenia was present in 36%; osteoporosis in 23%. Based on the reference population the expected prevalence was 15% and 1%, respectively. Prevalence of vitamin D deficiency was 50% (defined as a 25-OH vitamin D level < 50 nmol L-1 ). Mean self-reported BPAQ score was 19·4 units (reference interval 19-24). Multiple linear regression analysis showed a significant influence of vitamin D deficiency and bone-relevant physical exercise score on BMD in patients with EPP. CONCLUSIONS: The prevalence of osteoporosis and osteopenia is greatly increased in patients with EPP. Alkaline phosphatase (related to vitamin D deficiency) and amount of weight-bearing exercise are significantly correlated with low BMD in this population.

Severe tracheal and bronchial collapse in adults with type II mucopolysaccharidosis.

BACKGROUND: Mucopolysaccharidosis type II (MPSII) patients frequently suffer from dyspnoea caused by restrictive airway disease due to skeletal abnormalities as well as glycosaminoglycans (GAG) accumulation at different levels of the airway, including the trachea. In this study we describe the extent of the tracheal and bronchial narrowing, the changes in airway diameter during respiration and the effects of these obstructions on respiratory function in adult MPSII patients. METHODS: Five adult MPSII patients (mean age 40 years) were included. Pulmonary function tests and in- and expiratory chest CT scans were obtained. Cross-sectional areas of trachea and main bronchi were measured at end-inspiration and -expiration and percentage collapse was calculated. RESULTS: There was diffuse narrowing of the entire intra-thoracic trachea and main bronchi and severe expiratory collapse of the trachea in all patients. At 1 cm above the aortic arch the median % collapse of the trachea was 68 (range 60 to 77%), at the level of the aortic arch 64 (range 21-93%), for the main bronchi this was 58 (range 26-66%) on the left and 44 (range 9-76%) on the right side. The pulmonary function tests showed that this airway collapse results in obstructive airway disease in all patients, which was severe (forced expiratory volume <50% of predicted) in four out of five patients. CONCLUSION: In adult MPS II patients, central airways diameters are strikingly reduced and upon expiration there is extensive collapse of the trachea and main bronchi. This central airways obstruction explains the severe respiratory symptoms in MPSII patients.

Aceruloplasminemia presents as Type 1 diabetes in non-obese adults: a detailed case series.

AIM: To detect features that might lead to the early diagnosis and treatment of aceruloplasminemia, as initiation of treatment before the onset of neurological symptoms is likely to prevent neurological deterioration. METHODS: The PubMed and OMIM databases were searched for published cases of aceruloplasminemia. Diagnostic criteria for aceruloplasminemia were undetectable or very low serum ceruloplasmin, hyperferritinemia and low transferrin saturation. Clinical, biochemical and radiological data on the presentation and follow-up of the cases were extracted and completed through e-mail contact with all authors. RESULTS: We present an overview of 55 aceruloplasminemia cases, including three previously unreported cases. Diabetes mellitus was the first symptom related to aceruloplasminemia in 68.5% of the patients, manifesting at a median age of 38.5 years, and often accompanied by microcytic or normocytic anaemia. The combination preceded neurological symptoms in almost 90% of the neurologically symptomatic patients and was found 12.5 years before the onset of neurological symptoms. CONCLUSIONS: There is a diagnostic window during which diabetes and anaemia are present although there is an absence of neurological symptoms. Screening for aceruloplasminemia in adult non-obese individuals presenting with antibody-negative, insulin-dependent diabetes mellitus and unexplained anaemia is recommended. The combination of ferritin and transferrin saturation provides a sensitive initial measure for aceruloplasminemia.

Predicting non-adherence in patients with familial hypercholesterolemia.

PURPOSE: Familial hypercholesterolemia (FH) is an autosomal dominant disorder associated with a high risk of premature coronary heart disease (CHD). CHD prevention consists of lifestyle changes combined with lifelong statin treatment. Good adherence to statins reduces the risk of events substantially. This study was designed to identify determinants of non-adherence and to develop a model predicting non-adherence. METHODS: A single centre survey included all consecutive heterozygous FH patients above age 18 years, who were treated by a specialized team in the outpatient clinic of a university hospital in The Netherlands between 2008 and 2009. In addition to clinical data, patients completed a questionnaire concerning medication adherence. RESULTS: We analyzed 321 patients (169 women) with a statin prescription whose mean age was 46 ± 14 years (± S.D.), and 13 % of the patients had CHD. The untreated mean total cholesterol was 10 ± 2.3 mmol/l. On average, patients were ten years on cholesterol-lowering therapy (range 1-29 years). Adherence was reported by 89 % of the patients (> 90 % adherence). Non-adherence was associated with younger age (OR = 10.64, 95 % CI 2.86-39.68), high total cholesterol level during prescription (OR = 4.29, 95 % CI 1.86-9.89) and a relatively low untreated total cholesterol level (OR = 3.94 95 % CI 1.39-11.14). A prediction model based on these three determinants had a c-index of 0.78 and a calibration with P = 0.88. CONCLUSION: Based on three independent determinants, a prediction model is developed to identify non-adherent FH patients. This model needs to be tested in future prospective research. It might be a first step in improving statin adherence in this extremely high risk group.

Altered neuroregulation of GH secretion in viscerally obese premenopausal women.

We used deconvolution analysis of 24-h plasma GH concentration profiles (10- min sampling intervals) to appraise GH secretion rates and elimination kinetics in obese (body mass index, approximately 34 kg/m2) premenopausal women with large visceral fat area (LVFA; n = 8) vs. small visceral fat area (SVFA; n = 8) as determined by magnetic resonance imaging. The subjects were matched for body mass index, body fat percentage, and age. The impact of the loss of 50% of prestudy weight excess induced by caloric restriction was assessed as well. The results were compared with those obtained in normal weight control women (n = 8). LVFA subjects manifested markedly (4-fold) reduced mean plasma GH levels, which was brought about by jointly diminished basal and pulsatile GH secretion. Moreover, visceral obesity was associated with loss of regularity of GH release, as established by the approximate entropy statistic. In contrast, SVFA subjects produced normal daily amounts of GH and exhibited mean 24-h plasma GH concentrations that were similar to those in normal weight controls. GH half-life and distribution volume were not different among the study groups. Importantly, weight loss did not affect the daily GH secretion rate in LVFA women, so that their mean plasma GH concentration remained considerably reduced (approximately 50%) compared with controls (despite the loss of approximately 40% of visceral fat). Normal GH kinetics in SVFA women were not significantly influenced by weight reduction. Thus, GH neuroregulation appears to be particularly altered in obese women with a tendency to store fat in their visceral adipose depot. Because weight loss did not reverse GH secretion rate in viscerally obese women, we speculate that relative hyposomatotropism is a primary feature of these women, which could be involved in their tendency to preferentially store excess fat in visceral adipose tissue.

Estimation of growth hormone secretion rate: impact of kinetic assumptions intrinsic to the analytical approach.

We compared four common mathematical techniques to determine daily endogenous growth hormone (GH) secretion rates from diurnal plasma GH concentration profiles in 24 women (16 upper- or lower-body obese and 8 normal-weight individuals). Two forms of deconvolution analysis and two techniques based on a priori determined GH clearance estimates were employed. Deconvolution analyses revealed significant differences in the 24-h GH secretion rate between normal-weight and upper-body obese women, whereas the other two techniques did not. Moreover, deconvolution analyses predicted that the reduction in mean plasma GH concentrations in upper-body obese women was accounted for by impaired GH secretion, whereas the other methods suggested that obesity increases GH metabolic clearance. Thus we infer that disparate conclusions concerning GH secretion can be drawn from the same primary data set. The different inferences likely reflect dissimilar kinetic assumptions and the particular limitations intrinsic to each analytical approach. Accordingly, we urge caution in the facile comparison of calculated GH secretion data in humans, especially when kinetic and secretion measurements are performed under different conditions. The most appropriate way to determine the GH secretion rate in humans must be balanced by the exact intent of the experiment and the acceptability of different assumptions in that context.

Influence of obesity and body fat distribution on growth hormone kinetics in humans.

We studied the kinetics of exogenous recombinant 22-kDa human growth hormone (rhGH) in premenopausal women with upper body obesity (UBO), lower body obesity (LBO), or normal body weight. A bolus of 100 mU rhGH was administered during a continuous infusion of somatostatin to suppress endogenous GH secretion. GH kinetics were investigated with noncompartmental analysis of plasma GH curves. GH peak values in response to GH infusion and plasma half-life of GH were not significantly different between normal weight and obese subjects. In contrast, GH clearance was 33% higher in LBO women and 51% higher in UBO women compared with clearance in normal weight controls. The difference in clearance between LBO and UBO was not statistically significant. Altered GH clearance characteristics contribute to low circulating GH levels in obese humans. Body fat distribution does not appear to affect GH kinetics.

Circadian rhythm of plasma leptin levels in upper and lower body obese women: influence of body fat distribution and weight loss.

Plasma leptin concentrations were measured every 20 min for 24 h in eight normal weight women and in eight upper body and eight lower body obese women matched for body mass index. The circadian rhythm of leptin, which could mathematically be described by a cosine, was characterized by an acrophase just after midnight in all subjects. The amplitude of a cosine fit as well as the average 24-h leptin concentration were increased by 280% and 420%, respectively, in obese compared to normal weight women. All characteristics of leptin concentration profiles were similar in upper body and lower body obese women, except for a significantly higher amplitude in the lower body obese group. Visceral and sc body fat depots were measured using magnetic resonance imaging in all three groups. Average 24-h leptin concentrations were strongly correlated with sc fat (r = 0.84), whereas visceral fat was not an independent predictor of the plasma leptin level. A loss of 50% of the overweight was associated with a 55% decrease in the average 24-h leptin concentrations in obese women (95% confidence interval, 12.3, 26.6), whereas the characteristics of the circadian rhythm of leptin remained unchanged. Finally, it was observed that a fasting plasma leptin concentration is not an acceptable indicator of the average leptin concentration over 24 h.