The heterogeneous cancer phenotype of individuals with biallelic germline pathogenic variants in CHEK2

PURPOSE

Females with biallelic CHEK2 germline pathogenic variants (gPVs) more often develop multiple breast cancers than individuals with monoallelic CHEK2 gPVs. This study is aimed at expanding the knowledge on the occurrence of other malignancies.

METHODS

Exome sequencing of individuals who developed multiple primary malignancies identified 3 individuals with the CHEK2 (NM_007194.4) c.1100del p.(Thr367MetfsTer15) loss-of-function gPV in a biallelic state. We collected the phenotypes of an additional cohort of individuals with CHEK2 biallelic gPVs (n = 291).

RESULTS

In total, 157 individuals (53.4%; 157/294 individuals) developed ≥1 (pre)malignancy. The most common (pre)malignancies next to breast cancer were colorectal- (n = 19), thyroid- (n = 19), and prostate (pre)malignancies (n = 12). Females with biallelic CHEK2 loss-of-function gPVs more frequently developed ≥2 (pre)malignancies and at an earlier age compared with females biallelic for the CHEK2 c.470T>C p.(Ile157Thr) missense variant. Furthermore, 26 males (31%; 26/84 males) with CHEK2 biallelic gPVs developed ≥1 (pre)malignancies of 15 origins.

CONCLUSION

Our study suggests that CHEK2 biallelic gPVs likely increase the susceptibility to develop multiple malignancies in various tissues, both in females and males. However, it is possible that a substantial proportion of individuals with CHEK2 biallelic gPVs is missed as diagnostic testing for CHEK2 often is limited to individuals who developed breast cancer.

Clinical phenotype of FOXP1 syndrome: parent-reported medical signs and symptoms in 40 individuals

BACKGROUND

The first studies on patients with forkhead-box protein P1 (FOXP1) syndrome reported associated global neurodevelopmental delay, autism symptomatology, dysmorphic features and cardiac and urogenital malformations. The aim of this study was to assess the prevalence of congenital abnormalities in an unbiased cohort of patients with FOXP1 syndrome and to document rare complications.

METHODS

Patients with FOXP1 syndrome were included, mostly diagnosed via whole-exome sequencing for neurodevelopmental delay. A parent-report questionnaire was used to assess medical signs and symptoms, including questions about features rated as most burdensome by patients and their family.

RESULTS

Forty individuals were included, 20 females and 20 males. The mean age at assessment was 13.2 years (median 8.5 years; range 2-54 years; ≥18 years n = 7). Seven adults were included. All patients had developmental problems, including cognitive, communication, social-emotional and motor delays. The most prevalent medical signs and symptoms include delayed bladder control, sleeping problems, hypermetropia, strabismus, sacral dimple, undescended testes, abnormal muscle tone and airway infections. The most burdensome complaints for patients with FOXP1 syndrome, as perceived by parents, include intellectual disability, impaired communication, behaviour problems, lack of age-appropriate self-reliance, attention problems and anxiety. According to parents, patients have quite similar reported symptoms, although incontinence, obsessions and a complex sensory profile have a higher ranking.

CONCLUSION

The results of this study may be used to further guide medical management and identify patient priorities for future research targeted on those features of FOXP1 syndrome that most impair quality of life of patients and their families.

Reanalysis of whole-exome sequencing (WES) data of children with neurodevelopmental disorders in a standard patient care context

This study aims to inform future genetic reanalysis management by evaluating the yield of whole-exome sequencing (WES) reanalysis in standard patient care in the Netherlands. Single-center data of 159 patients with a neurodevelopmental disorder (NDD), in which WES analysis and reanalysis were performed between January 1, 2014, and December 31, 2021, was retrospectively collected. Patients were included if they were under the age of 18 years at initial analysis and if this initial analysis did not result in a diagnosis. Demographic, phenotypic, and genotypic characteristics of patients were collected and analyzed. The primary outcomes of our study were (i) diagnostic yield at reanalysis, (ii) reasons for detecting a new possibly causal variant at reanalysis, (iii) unsolicited findings, and (iv) factors associated with positive result of reanalysis. In addition, we conducted a questionnaire study amongst the 7 genetic department in the Netherlands creating an overview of used techniques, yield, and organization of WES reanalysis. The single-center data show that in most cases, WES reanalysis was initiated by the clinical geneticist (65%) or treating physician (30%). The mean time between initial WES analysis and reanalysis was 3.7 years. A new (likely) pathogenic variant or VUS with a clear link to the phenotype was found in 20 initially negative cases, resulting in a diagnostic yield of 12.6%. In 75% of these patients, the diagnosis had clinical consequences, as for example, a screening plan for associated signs and symptoms could be devised. Most (32%) of the (likely) causal variants identified at WES reanalysis were discovered due to a newly described gene-disease association. In addition to the 12.6% diagnostic yield based on new diagnoses, reclassification of a variant of uncertain significance found at initial analysis led to a definite diagnosis in three patients. Diagnostic yield was higher in patients with dysmorphic features compared to patients without clear dysmorphic features (yield 27% vs. 6%; p = 0.001).

CONCLUSIONS

Our results show that WES reanalysis in patients with NDD in standard patient care leads to a substantial increase in genetic diagnoses. In the majority of newly diagnosed patients, the diagnosis had clinical consequences. Knowledge about the clinical impact of WES reanalysis, clinical characteristics associated with higher yield, and the yield per year after a negative WES in larger clinical cohorts is warranted to inform guidelines for genetic reanalysis. These guidelines will be of great value for pediatricians, pediatric rehabilitation specialists, and pediatric neurologists in daily care of patients with NDD.

WHAT IS KNOWN

• Whole exome sequencing can cost-effectively identify a genetic cause of intellectual disability in about 30-40% of patients. • WES reanalysis in a research setting can lead to a definitive diagnosis in 10-20% of previously exome negative cases.

WHAT IS NEW

• WES reanalysis in standard patient care resulted in a diagnostic yield of 13% in previously exome negative children with NDD. • The presence of dysmorphic features is associated with an increased diagnostic yield of WES reanalysis.

Using PRPP-Assessment for measuring change in everyday activities by home-based videos: An exploratory case series study in children with multiple disabilities

BACKGROUND

Currently, paediatric health care aims to use a child-centred tailor-made approach. In order to design tailored occupational therapy, the implementation of personalised occupation-based measurements that guide and evaluate goal setting and are responsive to change is necessary.

PURPOSE

Primarily, this study explored the potential of the Perceive, Recall, Plan, and Perform (PRPP) assessment to measure the change in the performance of children with multiple disabilities. As a secondary evaluation, the feasibility of the PRPP-Intervention in a home-based program to enable activities was described. The overall aim is to show the potential of the PRPP-Assessment as an outcome measure to use as a base for designing tailor-made person-centred care.

METHODS

An exploratory longitudinal multiple case series mixed-methods design was used. The PRPP-Assessment, scored by multiple raters, was conducted based on parent-provided videos. The assessed activities were chosen by the child and/or parents. Responsiveness was evaluated by hypotheses formulated a priori and by comparing measured change with change on concurrent measures: Goal Attainment Scaling (GAS) and Canadian Occupational Performance Measure (COPM). Over a 6-week period, children and their parents (or caregivers) participated in an online home-based video coaching program where parents were coached in the implementation of the training, based on the PRPP-Intervention, by paediatric occupational therapists on a weekly basis. The feasibility of the intervention was explored using semi-structured interviews with children, parents, and the treating occupational therapists and was analysed by directed content analysis.

RESULTS

Three out of 17 eligible children agreed to participate and completed post-intervention measurement, of which two completed the intervention. Quantitative results showed that eight out of nine activities improved on the PRPP-Assessment and the COPM, and nine improved on the GAS. In total, 13 out of 15 hypotheses for responsiveness were accepted. Participants experienced the intervention as successful and acceptable. Facilitators and concerns over demand, implementation, practicality, integration, and adaptation were shared.

CONCLUSION

The PRPP-Assessment showed the potential to measure change in a heterogeneous group of children. The results indicated a positive tendency for the intervention and also provide directions for further development.

Diagnostic Gene Panel Testing in (Non)-Syndromic Patients with Cleft Lip, Alveolus and/or Palate in the Netherlands

Objectives

Clefts of the lip, alveolus and/or palate (CLA/P) are the most common craniofacial congenital malformations in humans. These oral clefts can be divided into non-syndromic (isolated) and syndromic forms. Many cleft-related syndromes are clinically variable and genetically heterogeneous, making it challenging to distinguish syndromic from non-syndromic cases. Recognition of syndromic/genetic causes is important for personalized tailored care, identification of (unrecognized) comorbidities, and accurate genetic counseling. Therefore, next generation sequencing (NGS)-based targeted gene panel testing is increasingly implemented in diagnostics of CLA/P patients. In this retrospective study, we assess the yield of NGS gene panel testing in a cohort of CLA/P cases.

Methods

Whole exome sequencing (WES) followed by variant detection and interpretation in an a priori selected set of genes associated with CLA/P phenotypes was performed in 212 unrelated CLA/P patients after genetic counseling between 2015 and 2020. Medical records including family history and results of additional genetic tests were evaluated.

Results

In 24 CLA/P cases (11.3%), a pathogenic genetic variant was identified. Twenty out of these 24 had a genetic syndrome requiring specific monitoring and follow-up. Six of these 24 cases (25%) were presumed to be isolated CLA/P cases prior to testing, corresponding to 2.8% of the total cohort. In eight CLA/P cases (3.8%) without a diagnosis after NGS-based gene panel testing, a molecular diagnosis was established by additional genetic analyses (e.g., SNP array, single gene testing, trio WES).

Conclusion

This study illustrates NGS-based gene panel testing is a powerful diagnostic tool in the diagnostic workup of CLA/P patients. Also, in apparently isolated cases and non-familial cases, a genetic diagnosis can be identified. Early diagnosis facilitates personalized care for patients and accurate genetic counseling of their families.

The neurodevelopmental and facial phenotype in individuals with a TRIP12 variant

Haploinsufficiency of TRIP12 causes a neurodevelopmental disorder characterized by intellectual disability associated with epilepsy, autism spectrum disorder and dysmorphic features, also named Clark-Baraitser syndrome. Only a limited number of cases have been reported to date. We aimed to further delineate the TRIP12-associated phenotype and objectify characteristic facial traits through GestaltMatcher image analysis based on deep-learning algorithms in order to establish a TRIP12 gestalt. 38 individuals between 3 and 66 years (F = 20, M = 18) - 1 previously published and 37 novel individuals - were recruited through an ERN ITHACA call for collaboration. 35 TRIP12 variants were identified, including frameshift (n = 15) and nonsense (n = 6) variants, as well as missense (n = 5) and splice (n = 3) variants, intragenic deletions (n = 4) and two multigene deletions disrupting TRIP12. Though variable in severity, global developmental delay was noted in all individuals, with language deficit most pronounced. About half showed autistic features and susceptibility to obesity seemed inherent to this disorder. A more severe expression was noted in individuals with a missense variant. Facial analysis showed a clear gestalt including deep-set eyes with narrow palpebral fissures and fullness of the upper eyelids, downturned corners of the mouth and large, often low-set ears with prominent earlobes. We report the largest cohort to date of individuals with TRIP12 variants, further delineating the associated phenotype and introducing a facial gestalt. These findings will improve future counseling and patient guidance.

Perceive, Recall, Plan and Perform (PRPP)-Assessment Based on Parent-Provided Videos of Children with Mitochondrial Disorder: Action Design Research on Implementation Challenges

AIMS

Performing the Perceive, Recall, Plan and Perform (PRPP)-Assessment, using video material of everyday life, seems sensible to lower the patient burden, enhance ecological validity, and provide care at a distance. However, receipt of adequate video material is not self-evident and assessing videos can be challenging. Therefore, this study aims to optimize the process of gaining video material and to optimize the PRPP-Assessment based on parent-provided videos.

METHODS

An action design research method was used, focusing on implementation of the PRPP-Assessment based on parent-provided videos within the care of children with a mitochondrial disorder or similar symptoms.

RESULTS

Five cycles were conducted. To receive input, the cycles used videos of nine children performing activities, written feedback, and semi-structured interviews and focus groups comprising parents (n = 13), a teacher (n = 1), occupational therapists (n = 16), and other professionals (n = 2) . This led to successful implementation of the PRPP-Assessment. General lessons were learned on (1) instructing parents; (2) handling video material; (3) PRPP-Assessment based on parent-provided videos; and (4) PRPP-Assessment of children (with limited functional abilities).

CONCLUSIONS

Lessons learned should be implemented in practice and are incorporated into a manual to guide the implementation of video-based observations with PRPP-Assessment in practice.

Sacral abnormalities including caudal appendage, skeletal dysplasia, and prenatal cardiomyopathy associated with a pathogenic TAB2 variant in a 3-generation family

Haplo-insufficiency of the TGFβ-activated kinase 1 binding protein 2 (TAB2) gene is associated with short stature, facial dysmorphisms, connective tissue abnormalities, hearing loss, and cardiac disease. Skeletal dysplasia and sacral dimples are also found in a minority of patients. Here, we describe a 3-generation family with caudal appendage, other sacral anomalies, and skeletal abnormalities including hypoplasia of the iliac wings and scapulae, fusion of the carpal bones and stenosis of the spinal canal, as well as a remarkable course of prenatally-detected cardiomyopathy with characteristics changing over time. Genetic analysis showed a heterozygous nonsense variant in the TAB2 gene.

Episignature Mapping of TRIP12 Provides Functional Insight into Clark-Baraitser Syndrome

Clark-Baraitser syndrome is a rare autosomal dominant intellectual disability syndrome caused by pathogenic variants in the TRIP12 (Thyroid Hormone Receptor Interactor 12) gene. TRIP12 encodes an E3 ligase in the ubiquitin pathway. The ubiquitin pathway includes activating E1, conjugating E2 and ligating E3 enzymes which regulate the breakdown and sorting of proteins. This enzymatic pathway is crucial for physiological processes. A significant proportion of TRIP12 variants are currently classified as variants of unknown significance (VUS). Episignatures have been shown to represent a powerful diagnostic tool to resolve inconclusive genetic findings for Mendelian disorders and to re-classify VUSs. Here, we show the results of DNA methylation episignature analysis in 32 individuals with pathogenic, likely pathogenic and VUS variants in TRIP12. We identified a specific and sensitive DNA methylation (DNAm) episignature associated with pathogenic TRIP12 variants, establishing its utility as a clinical biomarker for Clark-Baraitser syndrome. In addition, we performed analysis of differentially methylated regions as well as functional correlation of the TRIP12 genome-wide methylation profile with the profiles of 56 additional neurodevelopmental disorders.

The Phenotypic Continuum of ATP1A3-Related Disorders

BACKGROUND AND OBJECTIVES

ATP1A3 is associated with a broad spectrum of predominantly neurologic disorders, which continues to expand beyond the initially defined phenotypes of alternating hemiplegia of childhood, rapid-onset dystonia parkinsonism, and cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss syndrome. This phenotypic variability makes it challenging to assess the pathogenicity of an ATP1A3 variant found in an undiagnosed patient. We describe the phenotypic features of individuals carrying a pathogenic/likely pathogenic ATP1A3 variant and perform a literature review of all ATP1A3 variants published thus far in association with human neurologic disease. Our aim is to demonstrate the heterogeneous clinical spectrum of the gene and look for phenotypic overlap between patients that will streamline the diagnostic process.

METHODS

Undiagnosed individuals with ATP1A3 variants were identified within the cohort of the Deciphering Developmental Disorders study with additional cases contributed by collaborators internationally. Detailed clinical data were collected with consent through a questionnaire completed by the referring clinicians. PubMed was searched for publications containing the term "ATP1A3" from 2004 to 2021.

RESULTS

Twenty-four individuals with a previously undiagnosed neurologic phenotype were found to carry 21 ATP1A3 variants. Eight variants have been previously published. Patients experienced on average 2-3 different types of paroxysmal events. Permanent neurologic features were common including microcephaly (7; 29%), ataxia (13; 54%), dystonia (10; 42%), and hypotonia (7; 29%). All patients had cognitive impairment. Neuropsychiatric diagnoses were reported in 16 (66.6%) individuals. Phenotypes were extremely varied, and most individuals did not fit clinical criteria for previously published phenotypes. On review of the literature, 1,108 individuals have been reported carrying 168 different ATP1A3 variants. The most common variants are associated with well-defined phenotypes, while more rare variants often result in very rare symptom correlations, such as are seen in our study. Combined Annotation-Dependent Depletion (CADD) scores of pathogenic and likely pathogenic variants were significantly higher and variants clustered within 6 regions of constraint.

DISCUSSION

Our study shows that looking for a combination of paroxysmal events, hyperkinesia, neuropsychiatric symptoms, and cognitive impairment and evaluating the CADD score and variant location can help identify an ATP1A3-related condition, rather than applying diagnostic criteria alone.

Tailored interviewing to uncover the perspectives of children with multiple disabilities on daily activities: A qualitative analyses of interview methods and interviewer skills

INTRODUCTION

Uncovering the perspective of children with multiple disabilities is important in health care to enable person-centred health care. For occupational therapists, uncovering the child perspective on meaningful activities is necessary to set appropriate goals for treatment. It is not always evident that children with multiple disabilities can express themselves in an interview. The interviewer should adapt his communication to the child. In literature, alternative communication is widely studied, but a clear algorithm for deciding what to use to successfully gain insight into the child perspective is missing. This study aims to identify helpful interview techniques and interviewer skills and how they can be used to effectively uncover the perspective of children.

METHODS

Videos of nine interviews with children with a mitochondrial disorder, conducted by an occupational therapist, were analysed by five researchers. The interviews were analysed to see how well the interviewee had obtained the child's perspectives followed by observation of communicative abilities of the child and the types of questions the interviewer asked. A qualitative directed content analysis of the semi-structured interviews followed.

FINDINGS

An interview pattern was observed in the children's communication leading to six successful interviews. Children communicated verbally on four different levels and also used non-verbal communication. The interviewer used five types of questions, which varied between and within the children. The content analysis resulted in two themes: parental influences and interviewer skills.

CONCLUSION

Results show the importance of matching the type of questions to the verbal communication level of the child and revealed several interviewer skills and techniques. An overview to guide tailor-made interviewing is presented. The interviewer has a major role in successful interviewing and thus in enabling the inclusion of the child perspective in research and care.

The reliability and validity of the perceive, recall, plan and perform assessment in children with a mitochondrial disorder

PURPOSE

To investigate the reliability and validity of the Perceive, Recall, Plan and Perform System of Task Analysis (PRPP-Assessment) by parent-provided videos of children with mitochondrial disorders.

METHODS

Videos of 13 children performing 3-7 activities each were the subject of study, resulting in 65 activities. These were scored using the PRPP-Assessment by 11 raters. Internal consistency was calculated with Cronbach's alpha. Intra-rater reliability was evaluated by Bland-Altman Plots on 44 PRPP-Assessment scores. Inter-rater reliability was calculated with ICC_Agreement on 128 PRPP-Assessment scores. Construct validity was assessed by comparing the PRPP-Assessment scores to the Canadian Occupational Performance Measure using Cohen's Kappa. PRPP-Assessments scores were evaluated with a multi-faceted Rasch Analysis.

RESULTS

Internal consistency was high (0.92). Intra-rater reliability was sufficient to be good (92-96% within the 95%-Limits of the Agreement). The ICC_Agreement for stage 1 Mastery Score showed acceptable inter-rater reliability (0.646). Stage 2 of the PRPP-Assessment showed low ICCs due to a lack of variability within the sample. Four out of six hypotheses on validity were accepted. Rasch's analysis demonstrated sound goodness-of-fit, and supported the validity of the PRPP-Assessment.

CONCLUSION

The PRPP-Assessment by parent-provided videos in this heterogenic group showed sufficient to good psychometric properties. In practice, careful task selection and formulating criterion is recommended.Implications for RehabilitationPRPP-Assessment by parent-provided videos is reliable and valid in the complex, heterogenous group of children with mitochondrial disordersThe PRPP-Assessment is suitable for children with mitochondrial disorders as it showed to contain familiar, functional and meaningful tasks and activities that fit with their level of functioningProfessionals should be aware that parents might not be used to the criterium-based frame of reference of the PRPP-AssessmentWhen applying the PRPP-Assessment, it is recommended to be careful in task selection and formulating the criterion.

Recurrent de novo missense variants across multiple histone H4 genes underlie a neurodevelopmental syndrome

Chromatin is essentially an array of nucleosomes, each of which consists of the DNA double-stranded fiber wrapped around a histone octamer. This organization supports cellular processes such as DNA replication, DNA transcription, and DNA repair in all eukaryotes. Human histone H4 is encoded by fourteen canonical histone H4 genes, all differing at the nucleotide level but encoding an invariant protein. Here, we present a cohort of 29 subjects with de novo missense variants in six H4 genes (H4C3, H4C4, H4C5, H4C6, H4C9, and H4C11) identified by whole-exome sequencing and matchmaking. All individuals present with neurodevelopmental features of intellectual disability and motor and/or gross developmental delay, while non-neurological features are more variable. Ten amino acids are affected, six recurrently, and are all located within the H4 core or C-terminal tail. These variants cluster to specific regions of the core H4 globular domain, where protein-protein interactions occur with either other histone subunits or histone chaperones. Functional consequences of the identified variants were evaluated in zebrafish embryos, which displayed abnormal general development, defective head organs, and reduced body axis length, providing compelling evidence for the causality of the reported disorder(s). While multiple developmental syndromes have been linked to chromatin-associated factors, missense-bearing histone variants (e.g., H3 oncohistones) are only recently emerging as a major cause of pathogenicity. Our findings establish a broader involvement of H4 variants in developmental syndromes.

Broadening the spectrum of loss-of-function variants in NPR-C-related extreme tall stature

Context

Natriuretic peptide receptor-C (NPR-C, encoded by NPR3) belongs to a family of cell membrane–integral proteins implicated in various physiological processes, including longitudinal bone growth. NPR-C acts as a clearance receptor of natriuretic peptides, including C-type natriuretic peptide (CNP), that stimulate the cGMP-forming guanylyl cyclase-coupled receptors NPR-A and NPR-B. Pathogenic variants in CNP, NPR2, and NPR3 may cause a tall stature phenotype associated with macrodactyly of the halluces and epiphyseal dysplasia.

Objective

Here we report on a boy with 2 novel biallelic inactivating variants of NPR3.

Methods

History and clinical characteristics were collected. Biochemical indices of natriuretic peptide clearance and in vitro cellular localization of NPR-C were studied to investigate causality of the identified variants.

Results

We identified 2 novel compound heterozygous NPR3 variants c.943G>A p.(Ala315Thr) and c.1294A>T p.(Ile432Phe) in a boy with tall stature and macrodactyly of the halluces. In silico analysis indicated decreased stability of NPR-C, presumably resulting in increased degradation or trafficking defects. Compared to other patients with NPR-C loss-of-function, the phenotype seemed to be milder: pseudo-epiphyses in hands and feet were absent, biochemical features were less severe, and there was some co-localization of p.(Ile432Phe) NPR-C with the cell membrane, as opposed to complete cytoplasmic retention.

Conclusion

With this report on a boy with tall stature and macrodactyly of the halluces we further broaden the genotypic and phenotypic spectrum of NPR-C-related tall stature.

Hearing loss, cleft palate, and congenital hip dysplasia in female carriers of an intragenic deletion of AMMECR1

Previously, mutations in the AMMECR1 gene have been described in six males with developmental delay, sensorineural hearing loss (SNHL) and/or congenital abnormalities, including fetal nuchal edema, fetal pericardial effusion, talipes, congenital hip dysplasia, elliptocytosis and cleft palate. In this report, we present three female relatives of a male fetus with an intragenic deletion in this X‐linked gene. All three women reported hearing loss and one was born with a soft cleft palate and hip dysplasia. The audiograms showed mild to moderate SNHL with a variable pattern of the affected frequencies. Immunohistochemical analysis of fetal cochlea was performed confirming the expression of AMMECR1 in the human inner ear. Since hearing loss, cleft palate and congenital hip dysplasia were reported before in male AMMECR1 point mutation carriers and AMMECR1 is expressed in fetal inner ear, we suggest that female carriers may display a partial phenotype in this X‐linked condition.

Natural history, outcome measures and trial readiness in LAMA2-related muscular dystrophy and SELENON-related myopathy in children and adults: protocol of the LAST STRONG study

BACKGROUND

SELENON (SEPN1)-related myopathy (SELENON-RM) is a rare congenital myopathy characterized by slowly progressive proximal muscle weakness, early onset spine rigidity and respiratory insufficiency. A muscular dystrophy caused by mutations in the LAMA2 gene (LAMA2-related muscular dystrophy, LAMA2-MD) has a similar clinical phenotype, with either a severe, early-onset due to complete Laminin subunit α2 deficiency (merosin-deficient congenital muscular dystrophy type 1A (MDC1A)), or a mild, childhood- or adult-onset due to partial Laminin subunit α2 deficiency. For both muscle diseases, no curative treatment options exist, yet promising preclinical studies are ongoing. Currently, there is a paucity on natural history data and appropriate clinical and functional outcome measures are needed to reach trial readiness.

METHODS

LAST STRONG is a natural history study in Dutch-speaking patients of all ages diagnosed with SELENON-RM or LAMA2-MD, starting August 2020. Patients have four visits at our hospital over a period of 1.5 year. At all visits, they undergo standardized neurological examination, hand-held dynamometry (age ≥ 5 years), functional measurements, questionnaires (patient report and/or parent proxy; age ≥ 2 years), muscle ultrasound including diaphragm, pulmonary function tests (spirometry, maximal inspiratory and expiratory pressure, sniff nasal inspiratory pressure; age ≥ 5 years), and accelerometry for 8 days (age ≥ 2 years); at visit one and three, they undergo cardiac evaluation (electrocardiogram, echocardiography; age ≥ 2 years), spine X-ray (age ≥ 2 years), dual-energy X-ray absorptiometry (DEXA-)scan (age ≥ 2 years) and full body magnetic resonance imaging (MRI) (age ≥ 10 years). All examinations are adapted to the patient's age and functional abilities. Correlation between key parameters within and between subsequent visits will be assessed.

DISCUSSION

Our study will describe the natural history of patients diagnosed with SELENON-RM or LAMA2-MD, enabling us to select relevant clinical and functional outcome measures for reaching clinical trial-readiness. Moreover, our detailed description (deep phenotyping) of the clinical features will optimize clinical management and will establish a well-characterized baseline cohort for prospective follow-up.

CONCLUSION

Our natural history study is an essential step for reaching trial readiness in SELENON-RM and LAMA2-MD.

TRIAL REGISTRATION

This study has been approved by medical ethical reviewing committee Region Arnhem-Nijmegen (NL64269.091.17, 2017-3911) and is registered at ClinicalTrial.gov ( NCT04478981 ).

High FGF-21 level in a cohort of 22 patients with Dravet Syndrome - Possible relationship with the disease outcomes

OBJECTIVE

Dravet syndrome (DS) is a severe and intractable form of epilepsy with prolonged seizures which may evolve to other seizure types and associated with mild to severe intellectual disabilities. Fibroblast Growth Factor 21 (FGF-21) is a stress hormone mediating metabolic and oxidative stress and circulating level of FGF-21 had been shown to increase in some patients with impairment of oxidative phosphorylation in muscles. In DS, FGF-21 is of interest for further study as mitochondrial oxidative stress was identified previously in patients.

METHODS

Plasma FGF-21 levels were compared between 22 DS patients and 22 normal controls and their clinical characteristics of DS patients at the time of plasma sampling were studied retrospectively. Besides, the relationships of FGF-21 level with intellectual development, seizure frequency, valproate treatment and types of SCN1A mutations were analyzed. Logarithmic transformation of FGF-21 levels was performed before comparison and statistical analysis.

RESULTS

Mean of log₁₀ FGF-21 level was significantly higher in DS patients when comparing with normal controls (p = 0.0042). Mean of log₁₀ FGF-21 level was significantly higher in DS patients with normal to mild ID versus mild to severe ID (p = 0.0193) and with valproate treatment versus without valproate treatment (p = 0.015). No significant difference was shown in FGF-21 level in DS patients with missense versus truncating SCN1A variants and no correlation could be demonstrated between seizure frequency and FGF-21 level.

SIGNIFICANCE

Significantly higher level of plasma FGF-21 was identified in DS patients. The high FGF-21 levels were shown to be associated with developmental outcome and valproate treatment. These results support further investigation on the relationship of FGF-21 with the clinical outcomes of DS and other related mechanism which is important for possible therapeutic development for this epileptic encephalopathy.

Phenotypic expansion of the BPTF-related neurodevelopmental disorder with dysmorphic facies and distal limb anomalies

Neurodevelopmental disorder with dysmorphic facies and distal limb anomalies (NEDDFL), defined primarily by developmental delay/intellectual disability, speech delay, postnatal microcephaly, and dysmorphic features, is a syndrome resulting from heterozygous variants in the dosage‐sensitive bromodomain PHD finger chromatin remodeler transcription factor BPTF gene. To date, only 11 individuals with NEDDFL due to de novo BPTF variants have been described. To expand the NEDDFL phenotypic spectrum, we describe the clinical features in 25 novel individuals with 20 distinct, clinically relevant variants in BPTF, including four individuals with inherited changes in BPTF. In addition to the previously described features, individuals in this cohort exhibited mild brain abnormalities, seizures, scoliosis, and a variety of ophthalmologic complications. These results further support the broad and multi‐faceted complications due to haploinsufficiency of BPTF.

Intracerebral hemorrhage in a neonate with an intragenic COL4A2 duplication

Intracerebral hemorrhage is rare in term born neonates. Besides several non‐genetic risk factors, pathogenic variants in COL4A1 and COL4A2 have been described to play a role in the pathophysiology of neonatal intracerebral hemorrhage. To the best of our knowledge, no intragenic COL4A2 duplications have been reported in humans to date. We report a neonate with intracerebral hemorrhage and a de novo intragenic COL4A2 duplication. Although it is not clear yet whether this genetic factor fully explains the clinical phenotype, it may have contributed at least as a risk factor for cerebral hemorrhage. Screening for intragenic COL4A1 and COL4A2 duplications as part of collagen IV diagnostics should be considered as part of the fetal and neonatal work‐up for unexplained cerebral hemorrhages and to collect more evidence of the pathogenicity of this genetic mechanism.

Six-year prospective follow-up study in 151 carriers of the mitochondrial DNA 3243 A>G variant

BACKGROUND

The mitochondrial DNA (mDNA) 3243A>G variant is the most common pathogenic variant of the mDNA. To interpret results of clinical trials in mitochondrial disease, it is important to have a clear understanding of the natural course of disease. To obtain more insight into the disease burden and the progression of disease in carriers of the mDNA 3243 A>G variant, we followed a cohort of 151 carriers from 61 families prospectively for up to 6 years.

METHODS

The disease severity was scored using the Newcastle Mitochondrial Disease Adult Scale (NMDAS), including SF-36 quality of life (QoL) scores. Heteroplasmy levels were measured in urinary epithelial cells (UEC), leucocytes and saliva. The progression of the disease was studied using linear mixed model analysis.

RESULTS

One hundred twenty-four carriers (out of 151) were symptomatic. Four clinical groups were identified: 1) classical mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes syndrome (n=7), 2) maternally inherited diabetes deafness syndrome (n=60), 3) 'other' (n=57) and 4) dormant carriers (n=27). A yearly increase of NMDAS score of 0.47 point was measured in the total group. Heteroplasmy levels in both leucocytes and UEC were only weakly correlated with disease severity. Physical QoL declined with age. The most important determinants of QoL decline were hearing loss, speech problems, exercise intolerance, gait instability, psychiatric problems and gastrointestinal involvement.

CONCLUSION

The mDNA 3243 A>G variant causes a slowly progressive disease, with a yearly increase of NMDAS score of ~0.5 point overall with the clinical phenotype being the only determinant of disease progression.

Psychological functioning in children suspected for mitochondrial disease: the need for care

Background

Mitochondrial diseases (MD) are generally serious and progressive, inherited metabolic diseases. There is a high comorbidity of anxiety and depression and limitations in daily functioning. The complexity and duration of the diagnostic process and lack of knowledge about prognosis leads to uncertainty. In this study, we investigated the psychological well-being of children who are suspected for MD and their parents.

Methods

In total 122 children suspected for MD and their parents, received questionnaires as part of standard clinical investigation.

Results

Parent proxy report revealed a lower quality of life (QoL) compared to norms and even more physical problems compared to chronically ill patients. They also reported more behavioral problems in general and more internalizing problems compared to the norms. Most frequent reported somatic complaints were tiredness and pain. Parents did not report enhanced levels of stress regarding parenting and experienced sufficient social support. At the end of the diagnostic process, 5.7% of the children received the genetically confirmed diagnosis of MD, 26% showed non-conclusive abnormalities in the muscle biopsy, 54% did not receive any diagnosis, and the remaining received other diagnoses. Strikingly, children without a diagnosis showed equally QoL and behavioral problems as children with a diagnosis, and even more internalizing problems.

Conclusions

This study highlights the psychological concerns of children with a suspicion of MD. It is important to realize that as well as children with a confirmed diagnosis, children without a diagnosis are vulnerable since explanation for their complaints is still lacking.

Natural variability of daily physical activity measured by accelerometry in children with a mitochondrial disease

In this exploratory study we aimed to select the most valid and feasible accelerometer to measure daily physical activity at home in 10 children with mitochondrial disease. Using the experimentally-selected GENEActiv, good to excellent short- and long-term test-retest reliability of daily physical activity was found. Especially in children with more severe limitations daily physical activity seemed more stable and less susceptible to weather conditions. Moreover, small standard errors of measurement were found, indicating high precision of this measuring method. We conclude that measuring daily physical activity using accelerometry is a promising outcome measure for future studies in this unique population.

Mitochondrial Migraine: Disentangling the angiopathy paradigm in m.3243A>G patients

Migraine, characterized by recurrent attacks of predominantly unilateral throbbing headache, affects approximately 15% of the adult population and is an important cause of disability worldwide. Knowledge required for the development of new classes of antimigraine drugs might come from studying rare metabolic diseases associated with migraine. An illustrative example of a monogenetic disorder associated with migraine is the spectrum of disorders caused by the m.3243A>G mutation in the mitochondrial transfer RNA Leucine. Reported migraine prevalence figures in patients with this particular mutation vary considerably, but compared to the general population, m.3243A>G patients have a higher migraine prevalence. This burdensome symptom might sometimes even be the only clinical feature in maternal relatives carrying the m.3243A>G mutation. Although the exact sequence of events and the relative importance of factors underlying migraine in m.3243A>G MELAS spectrum disorders are still enigmatic, substantial evidence in man exist that dysfunctional mitochondria in both the vascular, the smooth muscle cells and the neuronal system and the interaction between these are at the starting point of the migraine developing pathophysiological cascade. Exclusively based on results of studies performed in patients harboring the m.3243A>G mutation, either in vivo or ex vivo, we here summarize our current understanding of mitochondrial angiopathy associated migraine in m.3243A>G patients which knowledge might lead to potential new avenues for migraine drug development.

Fear of disease progression in carriers of the m.3243A > G mutation

BACKGROUND

Being diagnosed with mitochondrial disease due to the m.3243A > G mutation is frequently preceded by a long diagnostic process. The disease itself is characterized by heterogeneous course and expression, so leaving patients with considerable uncertainty regarding their prognosis and treatment possibilities. This could easily result in fear of disease progression. This study investigated the presence of this fear and its correlates with genetic characteristics and clinical disease severity in m.3243A > G carriers.

METHODS

In total 125 eligible m.3243A > G mutation carriers were invited to participate in this cross-sectional study. After informed consent, participants completed questionnaires including items on socio-demographics, fear of progression, depression, anxiety, and quality of life. Clinical disease severity was assessed by the NMDAS questionnaire. Heteroplasmy levels were assessed in leucocytes, urine epithelial cells and buccal mucosa.

RESULTS

Seventy-six carriers participated in this study. Results showed that 18% reported high fear of progression. Fear of progression was significantly related to all domains of quality of life. Furthermore, fear of progression was moderately correlated with feelings of depression (r = .37), and anxiety (r = .44). Patients with moderate or severe clinical symptoms on the NMDAS experienced more fear of progression than patients with mild clinical symptoms. Fear of progression was weakly correlated with heteroplasmy in leucocytes (r = .27) and buccal mucosa (r = .31).

CONCLUSIONS

A substantial part of m.3243A > G mutation carriers experience high levels of fear of progression which coincide with significantly lower quality of life. Only a small relation with disease characteristics was found. The impact of receiving a diagnosis without therapeutic possibilities on fear is important to consider.

Outcome measures for children with mitochondrial disease: consensus recommendations for future studies from a Delphi-based international workshop

Although there are no effective disease-modifying therapies for mitochondrial diseases, an increasing number of trials are being conducted in this rare disease group. The use of sensitive and valid endpoints is essential to test the effectiveness of potential treatments. There is no consensus on which outcome measures to use in children with mitochondrial disease. The aims of this two-day Delphi-based workshop were to (i) define the protocol for an international, multi-centre natural history study in children with mitochondrial myopathy and (ii) to select appropriate outcome measures for a validation study in children with mitochondrial encephalopathy. We suggest two sets of outcome measures for a natural history study in children with mitochondrial myopathy and for a proposed validation study in children with mitochondrial encephalopathy.

The KHENERGY Study: Safety and Efficacy of KH176 in Mitochondrial m.3243A>G Spectrum Disorders

KH176 is a potent intracellular reduction-oxidation-modulating compound developed to treat mitochondrial disease. We studied tolerability, safety, pharmacokinetics, pharmacodynamics, and efficacy of twice daily oral 100 mg KH176 for 28 days in a double-blind, randomized, placebo-controlled, two-way crossover phase IIA study in 18 adult m.3243A>G patients without cardiovascular involvement. Efficacy parameters included clinical and functional outcome measures and biomarkers. The trial was registered within ClinicalTrials.gov (NCT02909400), the European Clinical Trials Database (2016-001696-79), and ISRCTN (43372293) (The KHENERGY study). Twice daily oral 100 mg KH176 was well tolerated and appeared safe. No serious treatment-emergent adverse events were reported. No significant improvements in gait parameters or other outcome measures were obtained, except for a positive effect on alertness and mood, although a coincidence due to multiplicity cannot be ignored. The results of the study provide first data on safety and efficacy of KH176 in patients with mitochondrial disease and will be instrumental in designing future clinical trials.

Quantification of gait in children with mitochondrial disease

Mitochondrial disorders are multisystem conditions that can potentially affect gait in many ways. The aim of this study was to select the optimal protocol to quantify the spatiotemporal parameters of gait in ambulatory children with mitochondrial disorders based on feasibility, test-retest reliability, and the difference between patients and controls. Gait at self-selected pace was quantified in ambulatory children with a genetically confirmed primary mitochondrial disease using the GAITRite electronic walkway. Three protocols were tested: pre-exercise, post-exercise (after a 3-min walking test), and recovery. In 14 ambulatory patients, we showed good to perfect reliability for velocity, cadence, step length, step time, step time variability, and step width in the recovery condition. The difference between patients and 70 individually age- and gender matched healthy controls only became apparent in the post-exercise protocol. In conclusion, measuring spatiotemporal parameters of gait using the GAITRite in ambulatory children with mitochondrial disease is feasible and reliable for most of the parameters measured. When using gait analysis in future studies in children with mitochondrial disease, we advise i) to use an exercise test prior to the gait analysis, ii) to let children practice the test before the actual data collection, and iii) not to use symmetry parameters.

KH176 under development for rare mitochondrial disease: a first in man randomized controlled clinical trial in healthy male volunteers

Background

Mitochondrial disorders are a clinically, biochemically and genetically heterogeneous group of multi-system diseases, with an unmet medical need for treatment. KH176 is an orally bio-available small molecule under development for the treatment of mitochondrial(−related) diseases. The compound is a member of a new class of drugs, acting as a potent intracellular redox-modulating agent essential for the control of oxidative and redox pathologies. The aim of this randomized, placebo controlled, double-blinded phase 1 study was to test safety, tolerability and pharmacokinetics of single and multiple doses of KH176 in healthy male volunteers. Putative effects on redox related biomarkers were explored.

Results

KH176 was well tolerated up to and including a single dose of 800 mg and multiple doses of 400 mg b.i.d. for 7 Days. However, when the QT interval was corrected for heart rate, administration of single doses of 800 and 2000 mg and at a multiple dose of 400 mg KH176 had marked effects. Post-hoc analysis of the ECGs showed clear changes in cardiac electrophysiology at single doses of 800 and 2000 mg and multiple doses of 400 mg b.i.d.. At lower doses, detailed ECG analysis showed no changes in electrophysiology compared to placebo. Exposure-response modelling of the cardiac intervals revealed an exposure range of KH176 without effects on cardiac conduction and provided a threshold of 1000 ng/mL above which changes in intervals could occur. After single- and multiple-dose administration, the pharmacokinetics of KH176 was more than dose proportional. KH176 accumulated to a small extent and food only slightly affected the pharmacokinetics of KH176, which was considered clinically irrelevant. Renal excretion of unchanged KH176 and its metabolite represents a minor pathway in the elimination of KH176. As expected in healthy volunteers no effects on redox biomarkers were observed.

Conclusion

The study deemed that KH176 is well tolerated up to single doses of 800 mg and multiple doses of 400 mg b.i.d. and has a pharmacokinetic profile supportive for a twice daily dosing. Only at high doses, KH176 causes clinically relevant changes in cardiac electrophysiology, including prolonged QTc interval and changes in T wave morphology. A Phase 2 clinical trial (100 mg b.i.d., orally) has been conducted recently of which the final results are expected Q1 2018.

Trial registration

NCT02544217. Registered. ISRCTN43372293. Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s13023-017-0715-0) contains supplementary material, which is available to authorized users.

Mitochondrial disorders in children: toward development of small-molecule treatment strategies

This review presents our current understanding of the pathophysiology and potential treatment strategies with respect to mitochondrial disease in children. We focus on pathologies due to mutations in nuclear DNA‐encoded structural and assembly factors of the mitochondrial oxidative phosphorylation (OXPHOS) system, with a particular emphasis on isolated mitochondrial complex I deficiency. Following a brief introduction into mitochondrial disease and OXPHOS function, an overview is provided of the diagnostic process in children with mitochondrial disorders. This includes the impact of whole‐exome sequencing and relevance of cellular complementation studies. Next, we briefly present how OXPHOS mutations can affect cellular parameters, primarily based on studies in patient‐derived fibroblasts, and how this information can be used for the rational design of small‐molecule treatment strategies. Finally, we discuss clinical trial design and provide an overview of small molecules that are currently being developed for treatment of mitochondrial disease.

Quantification of gait in mitochondrial m.3243A > G patients: a validation study

Background

More than half of the patients harbouring the m.3243A > G mutation were found to have trouble maintaining balance when walking in a recent study by our group. Others demonstrated that these patients had an abnormal gait pattern, as quantified by gait analysis. Gait analysis is an emerging method to quantify subtle changes in walking pattern, also during therapeutic interventions. Therefore, we aimed to test the reliability and reproducibility of gait analysis and select the most suitable protocol for this group of patients using a GAITRite electronic walkway. Four different protocols were tested: normal walking, dual task, post exercise and after a ten minutes of rest.

Results

In total 36 patients with the m.3243A > G mutation and 50 healthy controls were enrolled in this study. Overall high intra class correlation coefficients were found in all experimental conditions for both patients and healthy controls indicating good reproducibility. Marked differences in gait between patients and controls were observed and were in line with the only available exploratory study performed. There was a good correlation between both the overall NMDAS score, NMDAS subscale scores, both markers for disease severity, and specific gait parameters.

Conclusions

The observed reliability of the test makes GAITRite a suitable instrument for intervention studies in patients with mitochondrial disease.

Is 2D speckle tracking echocardiography useful for detecting and monitoring myocardial dysfunction in adult m.3243A>G carriers? - a retrospective pilot study

OBJECTIVES

Cardiomyopathy is a common complication of mitochondrial disorders, associated with increased mortality. Two dimensional speckle tracking echocardiography (2DSTE) can be used to quantify myocardial deformation. Here, we aimed to determine the usefulness of 2DSTE in detecting and monitoring subtle changes in myocardial dysfunction in carriers of the 3243A>G mutation in mitochondrial DNA.

METHODS

In this retrospective pilot study, 30 symptomatic and asymptomatic carriers of the mitochondrial 3243A>G mutation of whom two subsequent echocardiograms were available were included. We measured longitudinal, circumferential and radial strain using 2DSTE. Results were compared to published reference values.

RESULTS

Speckle tracking was feasible in 90 % of the patients for longitudinal strain. Circumferential and radial strain showed low face validity (low number of images with sufficient quality; suboptimal tracking) and were therefore rejected for further analysis. Global longitudinal strain showed good face validity, and was abnormal in 56-70 % (depending on reference values used) of the carriers (n = 27). Reproducibility was good (mean difference of 0.83 for inter- and 0.40 for intra-rater reproducibility; ICC 0.78 and 0.89, respectively). The difference between the first and the second measurement exceeded the measurement variance in 39 % of the cases (n = 23; feasibility of follow-up 77 %).

DISCUSSION

Even in data collected as part of clinical care, two-dimensional strain echocardiography seems a feasible method to detect and monitor subtle changes in longitudinal myocardial deformation in adult carriers of the mitochondrial 3243A>G mutation. Based on our data and the reported accuracy of global longitudinal strain in other studies, we suggest the use of global longitudinal strain in a prospective follow-up or intervention study.

Domains of Daily Physical Activity in Children with Mitochondrial Disease: A 3D Accelerometry Approach

Feasible, sensitive and clinically relevant outcome measures are of extreme importance when designing clinical trials. For paediatric mitochondrial disease, no robust end point has been described to date. The aim of this study was to select the domains of daily physical activity, which can be measured by 3D accelerometry, that could serve as sensitive end points in future clinical trials in children with mitochondrial disorders.In this exploratory observational study, 17 patients with mitochondrial disease and 16 age- and sex-matched controls wore 3D accelerometers at the upper leg, upper arm, lower arm and chest during one weekend. Using the raw data obtained by the accelerometers, we calculated the following outcome measures: (1) average amount of counts per hour the sensors were worn; (2) the maximal intensity; (3) the largest area under the curve during 30 min and (4) categorized activities lying, standing or being dynamically active. Measuring physical activity during the whole weekend was practically feasible in all participants. We found good face validity by visually correlating the validation videos and activity diaries to the accelerometer data-graphs. Patients with mitochondrial disorders had significantly lower peak intensity and were resting more, compared to their age- and sex-matched peers.Finally, we suggest domains of physical activity that could be included when measuring daily physical activity in children with mitochondrial disorders, preferably using more user-friendly devices. These include peak activity parameters for the arms (all patients) and legs (ambulatory patients). We recommend using or developing devices that measure these domains of physical activity in future clinical studies.

Radboud Centre for Mitochondrial Medicine Pediatric MRI score

We developed the first user-friendly, semi-quantitative, and quick-to-perform Radboud Centre for Mitochondrial Medicine Pediatric MRI score (RCMM-PMRIS), focusing on the six most commonly described neuroimaging abnormalities in the literature. The RCMM-PMRIS was validated through individual review of 30 sets of brain MRI studies in 24 patients with genetically confirmed mitochondrial disorders by six raters. The application of RCMM-PMRIS can help to define the extent of the brain involvement and therefore to assess the radiological mitochondrial disease severity, to monitor disease progression and consequently to act as an outcome measure for treatment effects in patients with mitochondrial disease.

International Paediatric Mitochondrial Disease Scale

OBJECTIVE

There is an urgent need for reliable and universally applicable outcome measures for children with mitochondrial diseases. In this study, we aimed to adapt the currently available Newcastle Paediatric Mitochondrial Disease Scale (NPMDS) to the International Paediatric Mitochondrial Disease Scale (IPMDS) during a Delphi-based process with input from international collaborators, patients and caretakers, as well as a pilot reliability study in eight patients. Subsequently, we aimed to test the feasibility, construct validity and reliability of the IPMDS in a multicentre study.

METHODS

A clinically, biochemically and genetically heterogeneous group of 17 patients (age 1.6-16 years) from five different expert centres from four different continents were evaluated in this study.

RESULTS

The feasibility of the IPMDS was good, as indicated by a low number of missing items (4 %) and the positive evaluation of patients, parents and users. Principal component analysis of our small sample identified three factors, which explained 57.9 % of the variance. Good construct validity was found using hypothesis testing. The overall interrater reliability was good [median intraclass correlation coefficient for agreement between raters (ICCagreement) 0.85; range 0.23-0.99).

CONCLUSION

In conclusion, we suggest using the IPMDS for assessing natural history in children with mitochondrial diseases. These data should be used to further explore construct validity of the IPMDS and to set age limits. In parallel, responsiveness and the minimal clinically important difference should be studied to facilitate sample size calculations in future clinical trials.

Quality of life, fatigue and mental health in patients with the m.3243A > G mutation and its correlates with genetic characteristics and disease manifestation

BACKGROUND

Mitochondrial disorders belong to the most prevalent inherited metabolic diseases with the m.3243A > G mutation reflecting being one of the most common mutations in mitochondrial DNA. Previous studies showed little relationship between mitochondrial genetics and disease manifestation. Relationship between genotype and disease manifestation with patient reported quality of life and other patient reported outcomes is still unexplored.

METHODS

Seventy-two out of the 122 invited adult patients with m.3243A > G mutation completed online standardized questionnaires on quality of life, functional impairment, fatigue and mental health as assessed by the RAND-SF36, the Sickness Impact Profile (SIP), the Checklist Individual Strength (CIS) and the Hospital Anxiety and Depression scale (HADS). Data were related to clinical manifestation reflected by the Newcastle Mitochondrial Disease Adult Scale (NMDAS) score and heteroplasmy levels of the mutation in urine epithelial cells.

RESULTS

Patients reported impaired quality of life. Sixty percent showed severe levels of fatigue, and 37% showed clinical relevant mental health problems, which was significantly more than healthy norms. These patient reported health outcomes showed negligible relationship with levels of heteroplasmy (r = <.30) and weak (.30 < r < .50) to moderate (.50 < r < .70) relationship with clinical manifestation.

CONCLUSIONS

Patient reported outcomes on quality of life, fatigue and mental health problems, are only partly reflected by clinical assessments. In order to support patients more effectively, integration of patient reported outcomes, alongside symptoms of their disease, in clinical practice is warranted.

Serum FGF21 levels in adult m.3243A>G carriers: clinical implications

OBJECTIVES

To determine the value of fibroblast growth factor 21 (FGF21), a recently discovered biomarker for mitochondrial disease, in predicting clinical disease severity and disease progression in adult carriers of the m.3243A>G mutation.

METHODS

In the context of a national inventory, the heteroplasmy levels of the m.3243A>G mutation were measured in leukocytes and urinary epithelial cells. The Newcastle Mitochondrial Disease Adult Scale score was determined and blood was drawn for measuring FGF21 concentration. Twenty-five of the included initial patients studied were then selected randomly for a follow-up study.

RESULTS

This prognostic study included 99 adult carriers of the m.3243A>G mutation. Our analysis revealed a moderate, significant correlation between FGF21 concentration and disease severity (r = 0.49; p = <0.001). No significant correlations were found between disease severity and the heteroplasmy percentage determined in urinary epithelial cells or the heteroplasmy percentage determined in leukocytes. Weak but significant correlations were also found between FGF21 concentration and the severity of the myopathy (r = 0.38; p = <0.001) and between the concentration of FGF21 and the severity of the encephalopathy (r = 0.30; p = <0.001). Repeated measurements following 25 subjects for 2 years revealed no significant correlation between FGF21 concentration and disease progression.

CONCLUSIONS

Measuring FGF21 concentration had little added value in monitoring and predicting the disease course in this specific patient group.

Towards the harmonization of outcome measures in children with mitochondrial disorders

AIM

A clinical trial is only as reliable as its outcomes, therefore the careful and systematic selection of outcome measures is extremely important. Currently, the selection of outcome measures for clinical trials designed to evaluate new drugs in patients with mitochondrial disorders is inefficient and has not been addressed systematically. Given that meaningful data can be obtained only from trials in which outcomes are assessed using valid instruments, one should first focus on the validation of a set of selected instruments in the target population. The aim of this review is to systematically select a 'toolbox' of robust outcome measures that are relevant to all patients.

METHOD

Using an extensive search of published literature, we systematically compiled a toolbox with outcome measures based on a primary search for possible instruments Subsequently, we reduced this toolbox using strict criteria that were adapted from the United States Food and Drug Administration.

RESULTS

A toolbox with clinically relevant and psychometrically robust instruments for performing clinical research in children with mitochondrial disorders was compiled.

INTERPRETATION

In coming years, more experience using these outcome measures in children with various mitochondrial disease phenotypes must be obtained before reliable conclusions regarding the validity of these instruments can be drawn.

Clinical features and heteroplasmy in blood, urine and saliva in 34 Dutch families carrying the m.3243A > G mutation

The m.3243A>G mutation has become known as the MELAS mutation. However, many other clinical phenotypes associated with this mutation have been described,most frequently being Maternally Inherited Diabetes and Deafness (MIDD). The m.3243A>G mutation, can be detected in virtually all tissues, however heteroplasmy differs between samples. Recent reports indicate, a preference to perform mutation analysis in Urinary Epithelial Cells(UEC). To test this, and to study a correlation between the mutational load in different tissues with two mitochondrial scoring systems (NMDAS and NPMDS) we investigated 34 families carrying the m.3243A>G mutation. Heteroplasmy was determined in three non-invasively collected samples,namely leucocytes, UEC and buccal mucosa. We included 127 patients, of which 82 carried the m.3243A>G mutation.None of the children (n011) had specific complaints. In adults(n071), a median NMDAS score of 15 (IQR 10-24) was found. The most prevalent symptoms were hearing loss(68 %), gastro-intestinal problems (59 %), exercise intolerance(54 %) and glucose intolerance (52 %). Ten patients had neurologic involvement. Buccal mucosa had the best correlation with the NMDAS in all adults (r00.437, p<0.001),whereas UEC had the strongest correlation with the NMDAS in severely affected patients (r00.593, p00.002). Heteroplasmy declined significantly with increasing age in all three samples (leucocytes r0-0.705 (p<0.001), UEC r0-0.374 (p00.001), buccal mucosa r0-0.460 (p<0.001). In our cohort of 82 patients, the m.3243A>Gmutation causes a wide variety of signs and symptoms, MIDD being far more prevalent than MELAS. Looking at the characteristics of the three noninvasively available tissues for testing heteroplasmy we confirm that UEC are the preferred sample to test [corrected].

Natural disease course and genotype-phenotype correlations in Complex I deficiency caused by nuclear gene defects: what we learned from 130 cases

Mitochondrial complex I is the largest multi-protein enzyme complex of the oxidative phosphorylation system. Seven subunits of this complex are encoded by the mitochondrial and the remainder by the nuclear genome. We review the natural disease course and signs and symptoms of 130 patients (four new cases and 126 from literature) with mutations in nuclear genes encoding structural complex I proteins or those involved in its assembly. Complex I deficiency caused by a nuclear gene defect is usually a non-dysmorphic syndrome, characterized by severe multi-system organ involvement and a poor prognosis. Age at presentation may vary, but is generally within the first year of life. The most prevalent symptoms include hypotonia, nystagmus, respiratory abnormalities, pyramidal signs, dystonia, psychomotor retardation or regression, failure to thrive, and feeding problems. Characteristic symptoms include brainstem involvement, optic atrophy and Leigh syndrome on MRI, either or not in combination with internal organ involvement and lactic acidemia. Virtually all children ultimately develop Leigh syndrome or leukoencephalopathy. Twenty-five percent of the patients died before the age of six months, more than half before the age of two and 75 % before the age of ten years. Some patients showed recovery of certain skills or are still alive in their thirties . No clinical, biochemical, or genetic parameters indicating longer survival were found. No clear genotype-phenotype correlations were observed, however defects in some genes seem to be associated with a better or poorer prognosis, cardiomyopathy, Leigh syndrome or brainstem lesions.