Should patients with Phosphomannomutase 2-CDG (PMM2-CDG) be screened for adrenal insufficiency?

PMM2-CDG is the most common congenital disorder of glycosylation (CDG) accounting for almost 65% of known CDG cases affecting N-glycosylation. Abnormalities in N-glycosylation could have a negative impact on many endocrine axes. There is very little known on the effect of impaired N-glycosylation on the hypothalamic-pituitary-adrenal axis function and whether CDG patients are at risk of secondary adrenal insufficiency and decreased adrenal cortisol production. Cortisol and ACTH concentrations were simultaneously measured between 7:44 am to 1 pm in forty-three subjects (20 female, median age 12.8 years, range 0.1 to 48.6 years) participating in an ongoing international, multi-center Natural History study for PMM2-CDG (ClinicalTrials.gov Identifier: NCT03173300). Of the 43 subjects, 11 (25.6%) had cortisol below 5 μg/dl and low to normal ACTH levels, suggestive of secondary adrenal insufficiency. Two of the 11 subjects have confirmed central adrenal insufficiency and are on hydrocortisone replacement and/or stress dosing during illness; 3 had normal and 1 had subnormal cortisol response to ACTH low-dose stimulation test but has not yet been started on therapy; the remaining 5 have upcoming stimulation testing planned. Our findings suggest that patients with PMM2-CDG may be at risk for adrenal insufficiency. Monitoring of morning cortisol and ACTH levels should be part of the standard care in patients with PMM2-CDG.Glycomine, Inc. was the sponsor of this study, and was involved in the study design and in the and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. Several authors of this publication are members of the European Reference Network for Rare Hereditary Metabolic Disorders (MetabERN) - Project ID No 739543.info:eu-repo/semantics/publishedVersio

Human and animal fertility studies in cystinosis reveal signs of obstructive azoospermia, an altered blood-testis barrier and a subtherapeutic effect of cysteamine in testis

Cystinosis is an inherited metabolic disorder caused by autosomal recessive mutations in the CTNS gene leading to lysosomal cystine accumulation. The disease primarily affects the kidneys followed by extra-renal organ involvement later in life. Azoospermia is one of the unclarified complications which are not improved by cysteamine, which is the only available disease-modifying treatment. We aimed at unraveling the origin of azoospermia in cysteamine-treated cystinosis by confirming or excluding an obstructive factor, and investigating the effect of cysteamine on fertility in the Ctns−/− mouse model compared with wild type. Azoospermia was present in the vast majority of infantile type cystinosis patients. While spermatogenesis was intact, an enlarged caput epididymis and reduced levels of seminal markers for obstruction neutral α-glucosidase (NAG) and extracellular matrix protein 1 (ECM1) pointed towards an epididymal obstruction. Histopathological examination in human and mouse testis revealed a disturbed blood-testis barrier characterized by an altered zonula occludens-1 (ZO-1) protein expression. Animal studies ruled out a negative effect of cysteamine on fertility, but showed that cystine accumulation in the testis is irresponsive to regular cysteamine treatment. We conclude that the azoospermia in infantile cystinosis is due to an obstruction related to epididymal dysfunction, irrespective of the severity of an evolving primary hypogonadism. Regular cysteamine treatment does not affect fertility but has subtherapeutic effects on cystine accumulation in testis

Monitoring phenylalanine concentrations in the follow-up of phenylketonuria patients:An inventory of pre-analytical and analytical variation

Background: Reliable measurement of phenylalanine (Phe) is a prerequisite for adequate follow-up of phenylketonuria (PKU) patients. However, previous studies have raised concerns on the intercomparability of plasma and dried blood spot (DBS) Phe results. In this study, we made an inventory of differences in (pre-)analytical methodology used for Phe determination across Dutch laboratories, and compared DBS and plasma results. Methods: Through an online questionnaire, we assessed (pre-)analytical Phe measurement procedures of seven Dutch metabolic laboratories. To investigate the difference between plasma and DBS Phe, participating laboratories received simultaneously collected plasma-DBS sets from 23 PKU patients. In parallel, 40 sample sets of DBS spotted from either venous blood or capillary fingerprick were analyzed. Results: Our data show that there is no consistency on standard operating procedures for Phe measurement. The association of DBS to plasma Phe concentration exhibits substantial inter-laboratory variation, ranging from a mean difference of −15.5% to +30.6% between plasma and DBS Phe concentrations. In addition, we found a mean difference of +5.8% in Phe concentration between capillary DBS and DBS prepared from venous blood. Conclusions: The results of our study point to substantial (pre-)analytical variation in Phe measurements, implicating that bloodspot Phe results should be interpreted with caution, especially when no correction factor is applied. To minimize variation, we advocate pre-analytical standardization and analytical harmonization of Phe measurements, including consensus on application of a correction factor to adjust DBS Phe to plasma concentrations

Couples with risk of a child with a mitochondrial disease:wat are the reproductive options?

Mitochondrial diseases are the most common inborn errors of metabolism. These severe multisystem disorders cause serious morbidity and mortality. Generally no treatment is available. This underlines the importance of counseling about the reproductive options to prevent the transmission of mitochondrial disorders. The majority of mitochondrial disorders is caused by a defect in a nuclear gene, in which cases the standard reproductive options can be applied, such as prenatal diagnosis (PND) and preimplantation genetic testing (PGT). For mitochondrial disorders caused by a mitochondrial DNA (mtDNA) mutation, reproductive options are determined by the recurrence risk, requiring specific reproductive counseling. For de novomtDNA mutations and inherited mtDNA mutations with a low recurrence risk, PND is possible. In case of a moderate or higher recurrence risk, PGT is the best option. In case the risk of a healthy embryo is (very) low, mitochondrial replacement therapy (MRT) may be a possibility in the future

Association of Body Composition, Physical Functioning, and Protein Intake in Adult Patients With Mitochondrial Diseases

Background Whether decreased physical functioning of patients with mitochondrial disease (MD) is related to altered body composition or low protein intake needs clarification at the background of the nutrition state. Methods In this 2‐site cross‐sectional study, MD patients were age‐, body mass index (BMI)–, and gender‐matched to controls. Body composition was assessed by dual‐energy x‐ray absorptiometry. Physical functioning was measured by handgrip strength, 6‐minute walking test, 30‐second sit‐to‐stand test (30SCT), and 6‐minute mastication test. Total daily protein intake was calculated by 3‐day food records. Malnutrition was assessed by Patient‐Generated Subjective Global Assessment and the Global Leadership Initiative on Malnutrition (GLIM) criteria and sarcopenia by the 2018 consensus. Data were analyzed using independent samples t‐tests, Fisher exact test, and Spearman and Pearson correlation coefficients. Results Thirty‐seven MD patients (42 ± 12 years, BMI: 23 ± 4 kg/m2, 59% females) and 37 matched controls were included. Handgrip strength was moderate, inversely related to fat mass index in both MD patients and controls, whereas it correlated with fat‐free mass index in controls solely. Protein intake was associated with muscle strength (handgrip strength and 30SCT) in MD patients but not in controls. Twenty‐seven MD patients (73%) were malnourished, and 5 (14%) were classified as sarcopenic. Conclusions Muscle strength is related to body composition and protein intake in MD patients. This, in combination with the high incidence of both malnutrition and sarcopenia, warrants individual nutrition assessment in MD patients.ISSN:0148-6071ISSN:1941-244

Social cognition, emotion-regulation and social competence in classical galactosemia patients without intellectual disability

Objective: Classical galactosemia (CG) is an inborn error of galactose metabolism. Many CG-patients suffer from long-Term complications including poor cognitive functioning. There are indications of social dysfunction but limited evidence in the literature. Therefore, this study aims to improve our understanding of social competence in CG by investigating social cognition, neurocognition and emotion-regulation. Methods: A comprehensive (neuro)psychological test battery including self-and proxy questionnaires was administered to CG-patients without intellectual disability. Social cognition was assessed by facial emotion recognition, Theory of Mind and self-reported empathy. Standardized results were compared to normative data of the general population. Results: Data of 23 patients (aged 8-52) were included in the study. On a group-level, CG-patients reported satisfaction with social roles and no social dysfunction despite the self-report of lower social skills. They showed deficits on all aspects of social cognition on both performance tests (emotion-recognition and Theory of Mind) and self-report questionnaires (empathy). Adults had a lower social participation than the general population. Parents reported lower social functioning, less adaptive emotion-regulation and communication difficulties in their children. Individual differences in scores were present. Conclusion: This study shows that CG patients without intellectual disability are satisfied with their social competence, especially social functioning. Nevertheless, deficits in social cognition are present in a large proportion of CG-patients. Due to the large variability in scores and discrepancies between self-and proxy-report, an individually tailored, comprehensive neuropsychological assessment including social cognition is advised in all CG-patients. Treatment plans need to be customized to the individual patient.</p

Three families with ‘de novo’ m.3243A > G mutation

The m.3243A > G mutation is the most prevalent, disease-causing mitochondrial DNA (mtDNA) mutation. In a national cohort study of 48 families harbouring the m.3243A > G mutation, we identified three families in which the mutation appeared to occur sporadically within these families. In this report we describe these three families. Based on detailed mtDNA analysis of three different tissues using two different quantitative pyrosequencing assays with sensitivity to a level of 1% mutated mtDNA, we conclude that the m.3243A > G mutation has arisen de novo in each of these families. The symptomatic carriers presented with a variety of symptoms frequently observed in patients harbouring the m.3243A > G mutation. A more severe phenotype is seen in the de novo families compared to recent cohort studies, which might be due to reporting bias. The observation that de novo m.3243A > G mutations exist is of relevance for both diagnostic investigations and genetic counselling. Firstly, even where there is no significant (maternal) family history in patients with stroke-like episodes, diabetes and deafness or other unexplained organ dysfunction, the m.3243A > G mutation should be screened as a possible cause of the disease. Second, analysis of maternally-related family members is highly recommended to provide reliable counselling for these families, given that the m.3243A > G mutation may have arisen de novo