Clinical, Neuroimaging, and Metabolic Footprint of the Neurodevelopmental Disorder Caused by Monoallelic HK1 Variants.

Background and Objectives: Hexokinase 1 (encoded by HK1) catalyzes the first step of glycolysis, the adenosine triphosphate-dependent phosphorylation of glucose to glucose-6-phosphate. Monoallelic HK1 variants causing a neurodevelopmental disorder (NDD) have been reported in 12 individuals. Methods: We investigated clinical phenotypes, brain MRIs, and the CSF of 15 previously unpublished individuals with monoallelic HK1 variants and an NDD phenotype. Results: All individuals had recurrent variants likely causing gain-of-function, representing mutational hot spots. Eight individuals (c.1370C>T) had a developmental and epileptic encephalopathy with infantile onset and virtually no development. Of the other 7 individuals (n = 6: c.1334C>T; n = 1: c.1240G>A), 3 adults showed a biphasic course of disease with a mild static encephalopathy since early childhood and an unanticipated progressive deterioration with, e.g., movement disorder, psychiatric disease, and stroke-like episodes, epilepsy, starting in adulthood. Individuals who clinically presented in the first months of life had (near)-normal initial neuroimaging and severe cerebral atrophy during follow-up. In older children and adults, we noted progressive involvement of basal ganglia including Leigh-like MRI patterns and cerebellar atrophy, with remarkable intraindividual variability. The CSF glucose and the CSF/blood glucose ratio were below the 5th percentile of normal in almost all CSF samples, while blood glucose was unremarkable. This biomarker profile resembles glucose transporter type 1 deficiency syndrome; however, in HK1-related NDD, CSF lactate was significantly increased in all patients resulting in a substantially different biomarker profile. Discussion: Genotype-phenotype correlations appear to exist for HK1 variants and can aid in counseling. A CSF biomarker profile with low glucose, low CSF/blood glucose, and high CSF lactate may point toward monoallelic HK1 variants causing an NDD. This can help in variant interpretation and may aid in understanding the pathomechanism. We hypothesize that progressive intoxication and/or ongoing energy deficiency lead to the clinical phenotypes and progressive neuroimaging findings.

Effect and safety of treatment with ACE-inhibitor Enalapril and ß-blocker metoprolol on the onset of left ventricular dysfunction in Duchenne muscular dystrophy - a randomized, double-blind, placebo-controlled trial.

BACKGROUND: X-linked Duchenne muscular dystrophy (DMD), the most frequent human hereditary skeletal muscle myopathy, inevitably leads to progressive dilated cardiomyopathy. We assessed the effect and safety of a combined treatment with the ACE-inhibitor enalapril and the ß-blocker metoprolol in a German cohort of infantile and juvenile DMD patients with preserved left ventricular function. METHODS TRIAL DESIGN: Sixteen weeks single-arm open run-in therapy with enalapril and metoprolol followed by a two-arm 1:1 randomized double-blind placebo-controlled treatment in a multicenter setting. INCLUSION CRITERIA: DMD boys aged 10-14 years with left ventricular fractional shortening [LV-FS] ≥ 30% in echocardiography. Primary endpoint: time from randomization to first occurrence of LV-FS < 28%. Secondary: changes of a) LV-FS from baseline, b) blood pressure, c), heart rate and autonomic function in ECG and Holter-ECG, e) cardiac biomarkers and neurohumeral serum parameters, f) quality of life, and g) adverse events. RESULTS: From 3/2010 to 12/2013, 38 patients from 10 sites were centrally randomized after run-in, with 21 patients continuing enalapril and metoprolol medication and 17 patients receiving placebo. Until end of study 12/2015, LV-FS < 28% was reached in 6/21 versus 7/17 patients. Cox regression adjusted for LV-FS after run-in showed a statistically non-significant benefit for medication over placebo (hazard ratio: 0.38; 95% confidence interval: 0.12 to 1.22; p = 0.10). Analysis of secondary outcome measures revealed a time-dependent deterioration of LV-FS with no statistically significant differences between the two study arms. Blood pressure, maximal heart rate and mean-NN values were significantly lower at the end of open run-in treatment compared to baseline. Outcome analysis 19 months after randomization displayed significantly lower maximum heart rate and higher noradrenalin and renin values in the intervention group. No difference between treatments was seen for quality of life. As a single, yet important adverse event, the reversible deterioration of walking abilities of one DMD patient during the run-in period was observed. CONCLUSIONS: Our analysis of enalapril and metoprolol treatment in DMD patients with preserved left ventricular function is suggestive to delay the progression of the intrinsic cardiomyopathy to left ventricular failure, but did not reach statistical significance, probably due to insufficient sample size. CLINICAL TRIAL REGISTRATION: DRKS-number 00000115, EudraCT-number 2009-009871-36.

Glycogen Storage Disease Type IV: A Rare Cause for Neuromuscular Disorders or Often Missed?

Advancements in genetic testing now allow early identification of previously unresolved neuromuscular phenotypes. To illustrate this, we here present diagnoses of glycogen storage disease IV (GSD IV) in two patients with hypotonia and delayed development of gross motor skills. Patient 1 was diagnosed with congenital myopathy based on a muscle biopsy at the age of 6 years. The genetic cause of his disorder (two compound heterozygous missense mutations in GBE1 (c.[760A>G] p.[Thr254Ala] and c.[1063C>T] p.[Arg355Cys])), however, was only identified at the age of 17, after panel sequencing of 314 genes associated with neuromuscular disorders. Thanks to the availability of next-generation sequencing, patient 2 was diagnosed before the age of 2 with two compound heterozygous mutations in GBE1 (c.[691+2T>C] (splice donor variant) and the same c.[760A>G] p.[Thr254Ala] mutation as patient 1). GSD IV is an autosomal recessive metabolic disorder with a broad and expanding clinical spectrum, which hampers targeted diagnostics. The current cases illustrate the value of novel genetic testing for rare genetic disorders with neuromuscular phenotypes, especially in case of clinical heterogeneity. We argue that genetic testing by gene panels or whole exome sequencing should be considered early in the diagnostic procedure of unresolved neuromuscular disorders.

Potential Risks to Stable Long-term Outcome of Allogeneic Hematopoietic Stem Cell Transplantation for Children With Cerebral X-linked Adrenoleukodystrophy.

Importance: Allogeneic hematopoietic stem cell transplantation is the standard intervention for childhood cerebral X-linked adrenoleukodystrophy. However, the pretransplant conditions, demyelination patterns, complications, and neurological outcomes of this therapy are not well characterized. Objectives: To identify the risks to stable neurocognitive survival after hematopoietic stem cell transplantation and to describe subgroups of patients with distinct clinical long-term outcomes. Design, Setting, and Participants: This case series analyzed the treatment and outcome of a cohort of 36 boys who underwent hematopoietic stem cell transplantation at Charité Universitätsmedizin Berlin, Germany, between January 1, 1997, and October 31, 2014. Case analysis was performed from January 1, 2016, through November 30, 2017. During this retrospective review, the adrenoleukodystrophy-disability rating score and the neurological function score were used. Demyelinating lesions in the brain were quantified by the Loes score. Main Outcomes and Measures: Overall survival, survival without major functional disabilities, and event-free survival were analyzed. Patients' clinical symptoms, demyelination patterns, and stem cell source were stratified. Results: Of the 36 boys who underwent hematopoietic stem cell transplantation, the median (range) age was 7.2 (4.2-15.4) years; 18 were presymptomatic and 18 were symptomatic. Twenty-seven patients (75%) were alive at a median (interquartile range [IQR]) follow-up of 108 (40-157) months. Sixteen of 18 presymptomatic patients (89%) survived, and 13 (72%) had an event-free survival with a median (IQR) survival time of 49 (37-115) months. Among the symptomatic patients, 11 of 18 (61%) survived, but only 1 was an event-free survival (6%) (median [IQR] time, 9 [3-22] months). Of the 9 patients who received a bone marrow transplant from a matched family donor, all survived. Among the 36 patients, 6 disease-related deaths (17%) and 3 transplant-related deaths (8%) occurred. Deaths from disease progression (n = 6) occurred only in patients with demyelination patterns other than parieto-occipital. In total, 18 patients (50%) displayed limited parieto-occipital (Loes score <9) or frontal (Loes score <4) demyelination before transplant (favorable). None of these patients died of progressive disease or developed major functional disabilities, 15 of them were characterized by stable neuroimaging after the transplant, and event-free survival was 77% (95% CI, 60%-100%). In contrast, the other 18 patients with more extended parieto-occipital demyelination (n = 6), frontal involvement (n = 4), or other demyelination patterns (n = 8) progressed (unfavorable): 13 patients developed epilepsy and 10 developed major functional disabilities, and their event-free survival was 0%. This newly defined neuroimaging assessment correlated best with neurocognitive deterioration after transplant (hazard ratio, 16.7; 95% CI, 4.7-59.6). Conclusions and Relevance: All patients with favorable neuroimaging who received matched bone marrow remained stable after transplant, while some of the other patients developed major functional disabilities. Newborn screening for the disease and regular neuroimaging are recommended, and patients who lack a matched bone marrow donor may need to find new therapeutic options.

ARHGEF9 disease: Phenotype clarification and genotype-phenotype correlation.

OBJECTIVE: We aimed to generate a review and description of the phenotypic and genotypic spectra of ARHGEF9 mutations. METHODS: Patients with mutations or chromosomal disruptions affecting ARHGEF9 were identified through our clinics and review of the literature. Detailed medical history and examination findings were obtained via a standardized questionnaire, or if this was not possible by reviewing the published phenotypic features. RESULTS: A total of 18 patients (including 5 females) were identified. Six had de novo, 5 had maternally inherited mutations, and 7 had chromosomal disruptions. All females had strongly skewed X-inactivation in favor of the abnormal X-chromosome. Symptoms presented in early childhood with delayed motor development alone or in combination with seizures. Intellectual disability was severe in most and moderate in patients with milder mutations. Males with severe intellectual disability had severe, often intractable, epilepsy and exhibited a particular facial dysmorphism. Patients with mutations in exon 9 affecting the protein's PH domain did not develop epilepsy. CONCLUSIONS: ARHGEF9 encodes a crucial neuronal synaptic protein; loss of function of which results in severe intellectual disability, epilepsy, and a particular facial dysmorphism. Loss of only the protein's PH domain function is associated with the absence of epilepsy.

Antibodies to MOG and AQP4 in children with neuromyelitis optica and limited forms of the disease.

OBJECTIVE: To determine the frequency and clinical-radiological associations of antibodies to myelin oligodendrocyte glycoprotein (MOG) and aquaporin-4 (AQP4) in children presenting with neuromyelitis optica (NMO) and limited forms. METHODS: Children with a first event of NMO, recurrent (RON), bilateral ON (BON), longitudinally extensive transverse myelitis (LETM) or brainstem syndrome (BS) with a clinical follow-up of more than 12 months were enrolled. Serum samples were tested for MOG- and AQP4-antibodies using live cell-based assays. RESULTS: 45 children with NMO (n=12), LETM (n=14), BON (n=6), RON (n=12) and BS (n=1) were included. 25/45 (56%) children had MOG-antibodies at initial presentation (7 NMO, 4 BON, 8 ON, 6 LETM). 5/45 (11%) children showed AQP4-antibodies (3 NMO, 1 LETM, 1 BS) and 15/45 (33%) were seronegative for both antibodies (2 NMO, 2 BON, 4 RON, 7 LETM). No differences were found in the age at presentation, sex ratio, frequency of oligoclonal bands or median EDSS at last follow-up between the three groups. Children with MOG-antibodies more frequently (1) had a monophasic course (p=0.018) after one year, (2) presented with simultaneous ON and LETM (p=0.004) and (3) were less likely to receive immunosuppressive therapies (p=0.0002). MRI in MOG-antibody positive patients (4) less frequently demonstrated periependymal lesions (p=0.001), (5) more often were unspecific (p=0.004) and (6) resolved more frequently (p=0.016). CONCLUSIONS: 67% of all children presenting with NMO or limited forms tested positive for MOG- or AQP4-antibodies. MOG-antibody positivity was associated with distinct features. We therefore recommend to measure both antibodies in children with demyelinating syndromes.

Intrauterine cardiomyopathy and cardiac mitochondrial proliferation in mitochondrial trifunctional protein (TFP) deficiency.

Because of a switch in energy-producing substrate utilization from glucose in the fetal period to fatty acids postnatally, intrauterine morbidity of fatty acid oxidation defects has widely been denied. We report the intrauterine development of severe cardiomyopathy in a child with mitochondrial trifunctional protein deficiency after 27 weeks of gestation. The child was born at 31 weeks of gestation and died on day 3 of life. Severe cardiac mitochondrial proliferation was observed. Molecular analysis of both TFP genes was performed and confirmed a homozygous mutation in the TFP alpha-subunit introducing a stop codon at amino acid position 256 (g.871C>T, p.R256X). Despite severe intrauterine decompensation in our patient, no HELLP-syndrome or acute fatty liver of pregnancy was observed in the mother. In the pathogenesis of maternal HELLP-syndrome, toxic effects of accumulating long-chain hydroxy-acyl-CoAs or long-chain hydroxy-acylcarnitines are suspected. In our patient, acylcarnitine analysis on day 2 of life during severest metabolic decompensation did not reveal massive accumulation of long-chain hydroxy-acylcarnitines in blood, suggesting other pathogenic factors than toxic effects. The most important pathogenic mechanism for the development of intrauterine cardiomyopathy appears to be significant cardiac energy deficiency. In conclusion, our report implicates that fatty acid oxidation does play a significant role during intrauterine development with special regard to the heart. Severe cardiac mitochondrial proliferation in TFP deficiency suggests pathophysiologically relevant energy deficiency in this condition.

Novel CCM1, CCM2, and CCM3 mutations in patients with cerebral cavernous malformations: in-frame deletion in CCM2 prevents formation of a CCM1/CCM2/CCM3 protein complex.

Cerebral cavernous malformations (CCM) are prevalent cerebrovascular lesions predisposing to chronic headaches, epilepsy, and hemorrhagic stroke. Using a combination of direct sequencing and MLPA analyses, we identified 15 novel and eight previously published CCM1 (KRIT1), CCM2, and CCM3 (PDCD10) mutations. The mutation detection rate was >90% for familial cases and >60% for isolated cases with multiple malformations. Splice site mutations constituted almost 20% of all CCM mutations identified. One of these proved to be a de novo mutation of the most 3' acceptor splice site of the CCM1 gene resulting in retention of intron 19. A further mutation affected the 3' splice site of CCM2 intron 2 leading to cryptic splice site utilization in both CCM2 and its transcript variant lacking exon 2. With the exception of one in-frame deletion of CCM2 exon 2, which corresponds to the naturally occurring splice variant of CCM2 on the RNA level and is predicted to result in the omission of 58 amino acids (CCM2:p.P11_K68del), all mutations lead to the introduction of premature stop codons. To gain insight into the likely mechanisms underlying the only known CCM2 in-frame deletion, we analyzed the functional consequences of loss of CCM2 exon 2. The CCM2:p.P11_K68del protein could be expressed in cell culture and complexed with CCM3. However, its ability to interact with CCM1 and to form a CCM1/CCM2/CCM3 complex was lost. These data are in agreement with a loss-of-function mechanism for CCM mutations, uncover an N-terminal CCM2 domain required for CCM1 binding, and demonstrate full-length CCM2 as the essential core protein in the CCM1/CCM2/CCM3 complex.

The phenotype and long-term follow-up in 11 patients with juvenile selenoprotein N1-related myopathy.

The selenoprotein N1-related myopathies comprise rigid spine muscular dystrophy, the "classical" form of multiminicore disease, a desmin-related myopathy with Mallory body like inclusions and a form of congenital fiber-type disproportion. To define the phenotype and long-term clinical course in juvenile Selenoprotein N1-related myopathies 11 juvenile patients from eight families with SEPN1 mutations were assessed over a mean period of 7.2 years. Clinical findings, histomorphological studies, respiratory investigations and genetic data were analyzed: age of manifestation varied within the first 2 years of life with muscle hypotonia, lag of head control and delayed motor development. Further gross motor development was normal in 9/11 patients. All patients were ambulant for at least 1000 m at a mean age of 13.7 years. Eight patients exhibited a rigid spine diagnosed at a mean age of 10 years. All patients had respiratory impairment with a vital capacity ranging from 18% to 65%. Four patients were intermittently nocturnally ventilated at a mean age of 11 years. Body mass index was below 20 (kgm(-2)) in all patients. Muscle biopsies of eight individuals revealed multiminicores (n=2), congenital fiber-type disproportion (n=1), myopathic changes with single cores (n=2) and unspecific myopathic features (n=3). Mutations were distributed throughout the entire SEPN1 gene. Although the phenotype of juvenile selenoprotein N1-related myopathies is homogenous regarding the main symptoms we describe a variable degree of clinical severity. Major complications were early respiratory failure, impaired increase in weight and orthopedic problems. There seems to be no correlation between skeletal muscle weakness and respiratory failure.

Biochemical and molecular characterization of 18 patients with pyridoxine-dependent epilepsy and mutations of the antiquitin (ALDH7A1) gene.

Patients with pyridoxine dependent epilepsy (PDE) present with early-onset seizures resistant to common anticonvulsants. According to the benefit of pyridoxine (vitamin B(6)) and recurrence of seizures on pyridoxine withdrawal, patients so far have been classified as having definite, probable, or possible PDE. Recently, PDE has been shown to be caused by a defect of alpha-amino adipic semialdehyde (AASA) dehydrogenase (antiquitin) in the cerebral lysine degradation pathway. The accumulating compound piperideine-6-carboxylic acid (P6C) was shown to inactivate pyridoxalphosphate (PLP) by a Knoevenagel condensation. Pipecolic acid (PA) and AASA are markedly elevated in urine, plasma, and cerebrospinal fluid (CSF) and thus can be used as biomarkers of the disease. We have investigated 18 patients with neonatal seizure onset, who have been classified as having definite (11), probable (four), or possible (three) PDE. All patients had elevated PA and AASA in plasma (and urine) while on treatment with individual dosages of pyridoxine. Within this cohort, molecular analysis identified 10 novel mutations (six missense mutations, one nonsense mutation, two splice site mutations) within highly conserved regions of the antiquitin gene. Seven mutations were located in exonic sequences and two in introns 7 and 17. Furthermore, a novel deletion of exon 7 was identified. Two of the 36 alleles investigated require further investigation. A known mutation (p.Glu399Gln) was found with marked prevalence, accounting for 12 out of 36 alleles (33%) within our cohort. Pyridoxine withdrawal is no longer needed to establish the diagnosis of "definite" PDE. Administration of pyridoxine in PDE may not only correct secondary PLP deficiency, but may also lead to a reduction of AASA (and P6C) as presumably toxic compounds.

Neonatal screening for citrullinaemia.

UNLABELLED: In a period of 40 months (1st March 1999 to 30th June 2002) 610,000 blood samples were analysed in one screening centre for citrulline as a pilot study for neonatal screening using tandem mass spectrometry. Persistent hypercitrullinaemia (Cit >1.5 mg/dl or 85.5 micro mol/l, not corrected for recovery) was identified in 15 newborns. Four children were diagnosed with classical neonatal onset citrullinaemia and eight with persisting asymptomatic hypercitrullinaemia. In two asymptomatic newborns and in one symptomatic preterm patient, argininosuccinate lyase deficiency was identified as the cause of moderately elevated levels of citrulline (cases not described in this paper). Citrulline concentrations were only temporarily mildly elevated in two newborns and in these the results of the original neonatal screening were therefore regarded as false-positive; we did not find any other false-positives. The screening result allowed the introduction of immediate specific treatment in two cases of citrullinaemia and may have prevented metabolic decompensation in those with presumed mild citrullinaemia. In one child who developed severe hyperammonaemia on the 2nd day of life, sequelae could not be avoided. CONCLUSION: neonatal screening for citrullinaemia is more complex than expected and, with the actual logistics, results may be obtained too late in severe forms.

EEG features of glut-1 deficiency syndrome.

PURPOSE: Glut-1 deficiency syndrome (Glut-1 DS) is caused by the deficiency of the major glucose transporter in cerebral microvessels. METHODS: We performed pre- and postprandial EEG recordings in two unrelated children with Glut-1 DS with developmental delay and seizures predominantly in the morning before breakfast. RESULTS: Extensive epileptiform discharges observed in the fasting state were improved markedly by food intake, as documented in EEG recordings 1 and 2 h after a meal. The ratio of cerebrospinal fluid glucose to blood glucose was decreased in both children. Glut-1 deficiency was confirmed by biochemical and molecular genetic investigations. CONCLUSIONS: Pre- and postprandial EEG recordings offer a simple screening test for Glut-1 DS.

Succinate in dystrophic white matter: a proton magnetic resonance spectroscopy finding characteristic for complex II deficiency.

A deficiency of succinate dehydrogenase is a rare cause of mitochondrial encephalomyopathy. Three patients, 2 sisters and 1 boy from an unrelated family, presented with symptoms and magnetic resonance imaging signs of leukoencephalopathy. Localized proton magnetic resonance spectroscopy indicated a prominent singlet at 2.40ppm in cerebral and cerebellar white matter not present in gray matter or basal ganglia. The signal was also elevated in cerebrospinal fluid and could be identified as originating from the two equivalent methylene groups of succinate. Subsequently, an isolated deficiency of complex II (succinate:ubiquinone oxidoreductase) was demonstrated in 2 patients in muscle and fibroblasts. One of the sisters died at the age of 18 months. Postmortem examination showed the neuropathological characteristics of Leigh syndrome. Her younger sister, now 12 months old, is also severely affected; the boy, now 6 years old, follows a milder, fluctuating clinical course. Magnetic resonance spectroscopy provides a characteristic pattern in succinate dehydrogenase deficiency.