Motor Responses in Pediatric Pompe Disease in the ADVANCE Participant Cohort.

BACKGROUND: ADVANCE (NCT01526785) presented an opportunity to obtain a more nuanced understanding of motor function changes in treatment-experienced children with Pompe disease receiving 4000L-production-scale alglucosidase alfa for 52 weeks. OBJECTIVE: To estimate minimal detectable change (MDC) and effect size on Gross Motor Function Measure-88 (GMFM-88) after 52 weeks of 4000L alglucosidase alfa (complete data N =  90). METHODS: The GMFM-88 mean total % score changes, MDC, and effect size were analyzed post hoc by Pompe Motor Function Level at enrollment, age groups at enrollment, and fraction of life on pre-study 160L-production-scale alglucosidase alfa. RESULTS: Overall, participants aged < 2 years surpassed MDC at Week 52 (change [mean±standard deviation] 21.1±14.1, MDC range 5.7-13.3, effect size 1.1), whereas participants aged≥2 years did not attain this (change -0.9±15.3, MDC range 10.8-25.2, effect size -0.03). In participants aged < 2 years, improvements surpassed the MDC for walkers (change 17.1±13.3, MDC range 3.0-6.9, effect size 1.7), supported standers (change 35.2±18.0, MDC range 5.9-13.7, effect size 1.8) and sitters (change 24.1±12.1, MDC range 2.6-6.2, effect size 2.7). Age-independent MDC ranges were only attained by walkers (change 7.7±12.3, MDC range 6.4-15.0, effect size 0.4) and sitters (change 9.9±17.2, MDC range 3.3-7.7, effect size 0.9). CONCLUSIONS: These first GMFM-88 minimal-detectable-change estimates for alglucosidase alfa-treated Pompe disease offer utility for monitoring motor skills. TRIAL REGISTRATION: ClinicalTrials.gov; NCT01526785; Registered 6 February 2012; https://clinicaltrials.gov/ct2/show/NCT01526785.

PRUNE1 c.933G>A synonymous variant induces exon 7 skipping, disrupts the DHHA2 domain, and leads to an atypical NMIHBA syndrome presentation: Case report and review of the literature.

Prune exopolyphosphatase-1 (PRUNE1) encodes a member of the aspartic acid-histidine-histidine (DHH) phosphodiesterase superfamily that regulates cell migration and proliferation during brain development. In 2015, biallelic PRUNE1 loss-of-function variants were identified to cause the neurodevelopmental disorder with microcephaly, hypotonia, and variable brain abnormalities (NMIHBA, OMIM#617481). NMIHBA is characterized by the namesake features and structural brain anomalies including thinning of the corpus callosum, cerebral and cerebellar atrophy, and delayed myelination. To date, 47 individuals have been reported in the literature, but the phenotypic spectrum of PRUNE1-related disorders and their causative variants remains to be characterized fully. Here, we report a novel homozygous PRUNE1 NM_021222.2:c.933G>A synonymous variant identified in a 6-year-old boy with intellectual and developmental disabilities, hypotonia, and spastic diplegia, but with the absence of microcephaly, brain anomalies, or seizures. Fibroblast RNA sequencing revealed that the PRUNE1 NM_021222.1:c.933G>A variant resulted in an in-frame skipping of the penultimate exon 7, removing 53 amino acids from an important protein domain. This case represents the first synonymous variant and the third pathogenic variant known to date affecting the DHH-associated domain (DHHA2 domain). These findings extend the genotypic and phenotypic spectrums in PRUNE1-related disorders and highlight the importance of considering synonymous splice site variants in atypical presentations.

Cardiac responses in paediatric Pompe disease in the ADVANCE patient cohort.

Pompe disease results from lysosomal acid α-glucosidase deficiency, which leads to cardiomyopathy in all infantile-onset and occasional late-onset patients. Cardiac assessment is important for its diagnosis and management. This article presents unpublished cardiac findings, concomitant medications, and cardiac efficacy and safety outcomes from the ADVANCE study; trajectories of patients with abnormal left ventricular mass z score at enrolment; and post hoc analyses of on-treatment left ventricular mass and systolic blood pressure z scores by disease phenotype, GAA genotype, and "fraction of life" (defined as the fraction of life on pre-study 160 L production-scale alglucosidase alfa). ADVANCE evaluated 52 weeks' treatment with 4000 L production-scale alglucosidase alfa in ≥1-year-old United States of America patients with Pompe disease previously receiving 160 L production-scale alglucosidase alfa. M-mode echocardiography and 12-lead electrocardiography were performed at enrolment and Week 52. Sixty-seven patients had complete left ventricular mass z scores, decreasing at Week 52 (infantile-onset patients, change -0.8 ± 1.83; 95% confidence interval -1.3 to -0.2; all patients, change -0.5 ± 1.71; 95% confidence interval -1.0 to -0.1). Patients with "fraction of life" <0.79 had left ventricular mass z score decreasing (enrolment: +0.1 ± 3.0; Week 52: -1.1 ± 2.0); those with "fraction of life" ≥0.79 remained stable (enrolment: -0.9 ± 1.5; Week 52: -0.9 ± 1.4). Systolic blood pressure z scores were stable from enrolment to Week 52, and no cohort developed systemic hypertension. Eight patients had Wolff-Parkinson-White syndrome. Cardiac hypertrophy and dysrhythmia in ADVANCE patients at or before enrolment were typical of Pompe disease. Four-thousand L alglucosidase alfa therapy maintained fractional shortening, left ventricular posterior and septal end-diastolic thicknesses, and improved left ventricular mass z score.Trial registry: ClinicalTrials.gov Identifier: NCT01526785 https://clinicaltrials.gov/ct2/show/NCT01526785.Social Media Statement: Post hoc analyses of the ADVANCE study cohort of 113 children support ongoing cardiac monitoring and concomitant management of children with Pompe disease on long-term alglucosidase alfa to functionally improve cardiomyopathy and/or dysrhythmia.

Hyperammonemia From Ureaplasma Infection in an Immunocompromised Child.

Idiopathic hyperammonemia is a rare, poorly understood, and often lethal condition that has been described in immunocompromised patients. This report describes an immunocompromised patient with acute myelogenous leukemia who developed persistent hyperammonemia up to 705 µmol/L (normal, 0 to 47 µmol/L) refractory to multiple different therapies. However, after beginning azithromycin and then doxycycline therapy for Ureaplasma species infection, the patient showed immediate and sustained clinical improvement and resolution of ammonia levels. Recognizing disseminated Ureaplasma species infection as a potential cause of idiopathic hyperammonemia, an unexplained, often fatal condition in immunocompromised patients, and empirically treating for this infection could potentially be lifesaving.

Clinical characteristics and genotypes in the ADVANCE baseline data set, a comprehensive cohort of US children and adolescents with Pompe disease.

PURPOSE: To characterize clinical characteristics and genotypes of patients in the ADVANCE study of 4000 L-scale alglucosidase alfa (NCT01526785), the largest prospective United States Pompe disease cohort to date. METHODS: Patients aged ≥1 year with confirmed Pompe disease previously receiving 160 L alglucosidase alfa were eligible. GAA genotypes were determined before/at enrollment. Baseline assessments included histories/physical exams, Gross Motor Function Measure-88 (GMFM-88), pulmonary function tests, and cardiac assessments. RESULTS: Of 113 enrollees (60 male/53 female) aged 1-18 years, 87 had infantile-onset Pompe disease (IOPD) and 26 late-onset (LOPD). One hundred eight enrollees with GAA genotypes had 215 pathogenic variants (220 including combinations): 118 missense (4 combinations), 23 splice, 35 nonsense, 34 insertions/deletions, 9 duplications (1 combination), 6 other; c.2560C>T (n = 23), c.-32-13T>G (n = 13), and c.525delT (n = 12) were most common. Four patients had previously unpublished variants, and 14/83 (17%) genotyped IOPD patients were cross-reactive immunological material-negative. All IOPD and 6/26 LOPD patients had cardiac involvement, all without c.-32-13T>G. Thirty-two (26 IOPD, 6 LOPD) were invasively ventilated. GMFM-88 total %scores (mean ± SD, median, range): overall 46.3 ± 33.0% (47.9%, 0.0-100.0%), IOPD 41.6 ± 31.64% (38.9%, 0.0-99.7%), LOPD: 61.8 ± 33.2 (70.9%, 0.0-100.0%). CONCLUSION: ADVANCE, a uniformly assessed cohort comprising most US children and adolescents with treated Pompe disease, expands understanding of the phenotype and observed variants in the United States.

Correction to: De novo and inherited TCF20 pathogenic variants are associated with intellectual disability, dysmorphic features, hypotonia, and neurological impairments with similarities to Smith-Magenis syndrome.

It was highlighted that the original article [1] contained a typographical error in the Results section. Subject 17 was incorrectly cited as Subject 1. This Correction article shows the revised statement. The original article has been updated.

De novo and inherited TCF20 pathogenic variants are associated with intellectual disability, dysmorphic features, hypotonia, and neurological impairments with similarities to Smith-Magenis syndrome.

BACKGROUND: Neurodevelopmental disorders are genetically and phenotypically heterogeneous encompassing developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASDs), structural brain abnormalities, and neurological manifestations with variants in a large number of genes (hundreds) associated. To date, a few de novo mutations potentially disrupting TCF20 function in patients with ID, ASD, and hypotonia have been reported. TCF20 encodes a transcriptional co-regulator structurally related to RAI1, the dosage-sensitive gene responsible for Smith-Magenis syndrome (deletion/haploinsufficiency) and Potocki-Lupski syndrome (duplication/triplosensitivity). METHODS: Genome-wide analyses by exome sequencing (ES) and chromosomal microarray analysis (CMA) identified individuals with heterozygous, likely damaging, loss-of-function alleles in TCF20. We implemented further molecular and clinical analyses to determine the inheritance of the pathogenic variant alleles and studied the spectrum of phenotypes. RESULTS: We report 25 unique inactivating single nucleotide variants/indels (1 missense, 1 canonical splice-site variant, 18 frameshift, and 5 nonsense) and 4 deletions of TCF20. The pathogenic variants were detected in 32 patients and 4 affected parents from 31 unrelated families. Among cases with available parental samples, the variants were de novo in 20 instances and inherited from 4 symptomatic parents in 5, including in one set of monozygotic twins. Two pathogenic loss-of-function variants were recurrent in unrelated families. Patients presented with a phenotype characterized by developmental delay, intellectual disability, hypotonia, variable dysmorphic features, movement disorders, and sleep disturbances. CONCLUSIONS: TCF20 pathogenic variants are associated with a novel syndrome manifesting clinical characteristics similar to those observed in Smith-Magenis syndrome. Together with previously described cases, the clinical entity of TCF20-associated neurodevelopmental disorders (TAND) emerges from a genotype-driven perspective.

Nonleaking cystoid macular edema in Cohen syndrome.

An 11-year-old girl with a history of neutropenia, developmental delay, hypotonia, and intellectual disability was diagnosed with Cohen syndrome after genetic testing discovered homozygous mutation in the VPS13B gene. She was referred to a retinal specialist with a chief complaint of decreased peripheral vision. On examination, decreased visual acuity, pigmentary changes, and nonleaking cystoid macular edema were present in both eyes.

Efficacy, safety profile, and immunogenicity of alglucosidase alfa produced at the 4,000-liter scale in US children and adolescents with Pompe disease: ADVANCE, a phase IV, open-label, prospective study.

PURPOSE: Pompe disease results from lysosomal acid α-glucosidase (GAA) deficiency and its associated glycogen accumulation and muscle damage. Alglucosidase alfa (recombinant human GAA (rhGAA)) received approval in 2006 as a treatment for Pompe disease at the 160 L production scale. In 2010, larger-scale rhGAA was approved for patients up to 8 years old without cardiomyopathy. NCT01526785 evaluated 4,000 L rhGAA efficacy/safety in US infantile- or late-onset Pompe disease (IOPD, LOPD) patients up to 1 year old transitioned from 160 L rhGAA. METHODS: A total of 113 patients (87 with IOPD; 26 with LOPD) received 4,000 L rhGAA for 52 weeks dosed the same as previous 160 L rhGAA. Efficacy was calculated as the percentage of patients stable/improved at week 52 (without death, new requirement for invasive ventilation, left ventricular mass z-score increase >1 if baseline was >2, upright forced vital capacity decrease ≥15% predicted, or Gross Motor Function Measure-88 decrease ≥8 percentage points). Safety evaluation included an extension ≤20 months. RESULTS: Week 52 data was available for 104 patients, 100 of whom entered the extension. At week 52, 87/104 (83.7%) were stable/improved. Overall survival was 98.1% overall, 97.6% IOPD, 100% LOPD; 92.4% remained invasive ventilator-free (93.4% IOPD, 88.7% LOPD). Thirty-five patients had infusion-associated reactions. Eight IOPD patients died of drug-unrelated causes. CONCLUSIONS: Most Pompe disease patients were clinically stable/improved after transitioning to 4,000 L rhGAA. Safety profiles of both rhGAA forms were consistent.

DYNAMIC RETINA VESSEL COLOR CHANGE DURING OCULAR COMPRESSION IN SEVERE LIPEMIA RETINALIS.

PURPOSE: The aim of this study was to describe dynamic color change in retinal vessels from white to coral pink due to externally applied ocular pressure in a 6-week-old infant with lipemia retinalis secondary to type 1b familial hyperlipoproteinemia. METHODS: Fundus images and fluorescein angiogram were taken with RetCam3 camera. Color photographs of pooled blood were taken during phlebotomy. RESULTS: Genetic analysis revealed a rare genetic mutation in the APOC2 gene, a lipoprotein lipase activator. Intraocular pressure applied to the globe induced a color change in the retinal arteries from white to coral pink. Disruption in laminar flow leading to this change is described. CONCLUSION: This is the first report to attribute the retinal vessel color change to disrupted laminar flow and the intermixing of larger erythrocytes and smaller chylomicrons in a patient with lipemia retinalis. In addition, this is a rare example of congenital hyperlipidemia in the offspring of nonconsanguineous parents.

Biallelic mutations in the ferredoxin reductase gene cause novel mitochondriopathy with optic atrophy.

Iron-sulfur (Fe-S) clusters are ubiquitous cofactors essential to various cellular processes, including mitochondrial respiration, DNA repair, and iron homeostasis. A steadily increasing number of disorders are being associated with disrupted biogenesis of Fe-S clusters. Here, we conducted whole-exome sequencing of patients with optic atrophy and other neurological signs of mitochondriopathy and identified 17 individuals from 13 unrelated families with recessive mutations in FDXR, encoding the mitochondrial membrane-associated flavoprotein ferrodoxin reductase required for electron transport from NADPH to cytochrome P450. In vitro enzymatic assays in patient fibroblast cells showed deficient ferredoxin NADP reductase activity and mitochondrial dysfunction evidenced by low oxygen consumption rates (OCRs), complex activities, ATP production and increased reactive oxygen species (ROS). Such defects were rescued by overexpression of wild-type FDXR. Moreover, we found that mice carrying a spontaneous mutation allelic to the most common mutation found in patients displayed progressive gait abnormalities and vision loss, in addition to biochemical defects consistent with the major clinical features of the disease. Taken together, these data provide the first demonstration that germline, hypomorphic mutations in FDXR cause a novel mitochondriopathy and optic atrophy in humans.

De Novo Disruption of the Proteasome Regulatory Subunit PSMD12 Causes a Syndromic Neurodevelopmental Disorder.

Degradation of proteins by the ubiquitin-proteasome system (UPS) is an essential biological process in the development of eukaryotic organisms. Dysregulation of this mechanism leads to numerous human neurodegenerative or neurodevelopmental disorders. Through a multi-center collaboration, we identified six de novo genomic deletions and four de novo point mutations involving PSMD12, encoding the non-ATPase subunit PSMD12 (aka RPN5) of the 19S regulator of 26S proteasome complex, in unrelated individuals with intellectual disability, congenital malformations, ophthalmologic anomalies, feeding difficulties, deafness, and subtle dysmorphic facial features. We observed reduced PSMD12 levels and an accumulation of ubiquitinated proteins without any impairment of proteasome catalytic activity. Our PSMD12 loss-of-function zebrafish CRISPR/Cas9 model exhibited microcephaly, decreased convolution of the renal tubules, and abnormal craniofacial morphology. Our data support the biological importance of PSMD12 as a scaffolding subunit in proteasome function during development and neurogenesis in particular; they enable the definition of a neurodevelopmental disorder due to PSMD12 variants, expanding the phenotypic spectrum of UPS-dependent disorders.

Homozygous variants in pyrroline-5-carboxylate reductase 2 (PYCR2) in patients with progressive microcephaly and hypomyelinating leukodystrophy.

Pyrroline-5-carboxylate reductase 2, encoded by PYCR2, is one of the three homologous enzymes that catalyze the last step of proline synthesis. Homozygous variants in PYCR2 have been reported in patients from multiple consanguineous families with hypomyelinating leukodystrophy 10 (HLD10) (MIM: 616420). Here, we report five additional patients from three families with homozygous nonsense or missense variants in PYCR2, identified through clinical exome sequencing. All patients presented with postnatally acquired microcephaly, moderate to profound global developmental delay, and failure to thrive. Brain MRI in these patients showed thin corpus callosum, delayed myelination, and generalized white-matter volume loss. Additional phenotypes that were less consistent among patients included seizures or seizure-like movements, spasticity and ataxic gait, recurrent vomiting, cortical blindness, dysmorphic features, joint contractures, and irritability. Exome sequencing identified homozygous variants in PYCR2 in the proband from each family: c.28C>T (p.(Glu10Ter)), c.796C>T (p.(Arg266Ter)), and c.577G>A (p.(Val193Met)). Subsequent targeted analyses demonstrated co-segregation of the disease with the variant in the family. Despite the metabolic role of PYCR2, routine serum metabolic test in these patients were normal. To further understand the disease etiology and functions of PYCR2, small molecule metabolomics profiling was performed in plasma from three severely affected patients. No significant changes were identified in proline biosynthesis pathway or related metabolites. Studying the clinical features and the metabolic profiles of the PYCR2-deficient patients provides a more comprehensive picture for this newly identified disorder and facilitates further research on the gene function and disease etiology. © 2016 Wiley Periodicals, Inc.

Recurrent ACADVL molecular findings in individuals with a positive newborn screen for very long chain acyl-coA dehydrogenase (VLCAD) deficiency in the United States.

Very long chain acyl-coA dehydrogenase deficiency (VLCADD) is an autosomal recessive inborn error of fatty acid oxidation detected by newborn screening (NBS). Follow-up molecular analyses are often required to clarify VLCADD-suggestive NBS results, but to date the outcome of these studies are not well described for the general screen-positive population. In the following study, we report the molecular findings for 693 unrelated patients that sequentially received Sanger sequence analysis of ACADVL as a result of a positive NBS for VLCADD. Highlighting the variable molecular underpinnings of this disorder, we identified 94 different pathogenic ACADVL variants (40 novel), as well as 134 variants of unknown clinical significance (VUSs). Evidence for the pathogenicity of a subset of recurrent VUSs was provided using multiple in silico analyses. Surprisingly, the most frequent finding in our cohort was carrier status, 57% all individuals had a single pathogenic variant or VUS. This result was further supported by follow-up array and/or acylcarnitine analysis that failed to provide evidence of a second pathogenic allele. Notably, exon-targeted array analysis of 131 individuals screen positive for VLCADD failed to identify copy number changes in ACADVL thus suggesting this test has a low yield in the setting of NBS follow-up. While no genotype was common, the c.848T>C (p.V283A) pathogenic variant was clearly the most frequent; at least one copy was found in ~10% of all individuals with a positive NBS. Clinical and biochemical data for seven unrelated patients homozygous for the p.V283A allele suggests that it results in a mild phenotype that responds well to standard treatment, but hypoglycemia can occur. Collectively, our data illustrate the molecular heterogeneity of VLCADD and provide novel insight into the outcomes of NBS for this disorder.

Expanding the Molecular and Clinical Phenotype of SSR4-CDG.

Congenital disorders of glycosylation (CDG) are a group of mostly autosomal recessive disorders primarily characterized by neurological abnormalities. Recently, we described a single CDG patient with a de novo mutation in the X-linked gene, Signal Sequence Receptor 4 (SSR4). We performed whole-exome sequencing to identify causal variants in several affected individuals who had either an undifferentiated neurological disorder or unsolved CDG of unknown etiology based on abnormal transferrin glycosylation. We now report eight affected males with either de novo (4) or inherited (4) loss of function mutations in SSR4. Western blot analysis revealed that the mutations caused a complete loss of SSR4 protein. In nearly all cases, the abnormal glycosylation of serum transferrin was only slightly above the accepted normal cutoff range.

Int22h-1/int22h-2-mediated Xq28 rearrangements: intellectual disability associated with duplications and in utero male lethality with deletions.

BACKGROUND: X linked intellectual disability (XLID) is common, with an estimated prevalence of 1/1000. The expanded use of array comparative genomic hybridisation (CGH) has led to the identification of several XLID-associated copy-number variants. METHODS: Array CGH analysis was performed using chromosomal microarray with ∼105 000 oligonucleotides covering the entire genome. Confirmatory fluorescence in situ hybridisation analyses were subsequently performed. Chromosome X-inactivation (XCI) was assessed using methylation-sensitive restriction enzyme digestion followed by PCR amplification. RESULTS: A novel ∼0.5 Mb duplication in Xq28 was identified in four cognitively impaired males who share behavioural abnormalities (hyperactivity and aggressiveness) and characteristic facial features (high forehead, upper eyelid fullness, broad nasal bridge and thick lower lip). These duplications were inherited from mothers with skewed XCI and are mediated by nonallelic homologous recombination between the low-copy repeat regions int22h-1 and int22h-2, which, in addition to int22h-3, are also responsible for inversions disrupting the factor VIII gene in haemophilia A. In addition, we have identified a reciprocal deletion in a girl and her mother, both of whom exhibit normal cognition and completely skewed XCI. The mother also had two spontaneous abortions. CONCLUSIONS: The phenotypic similarities among subjects with int22h-1/int22h-2-mediated Xq28 duplications suggest that such duplications are responsible for a novel XLID syndrome. The reciprocal deletion may not be associated with a clinical phenotype in carrier females due to skewed XCI, but may be lethal for males in utero. Advancements in array CGH technology have enabled the identification of such small, clinically relevant copy-number variants.

Detection of clinically relevant exonic copy-number changes by array CGH.

Array comparative genomic hybridization (aCGH) is a powerful tool for the molecular elucidation and diagnosis of disorders resulting from genomic copy-number variation (CNV). However, intragenic deletions or duplications--those including genomic intervals of a size smaller than a gene--have remained beyond the detection limit of most clinical aCGH analyses. Increasing array probe number improves genomic resolution, although higher cost may limit implementation, and enhanced detection of benign CNV can confound clinical interpretation. We designed an array with exonic coverage of selected disease and candidate genes and used it clinically to identify losses or gains throughout the genome involving at least one exon and as small as several hundred base pairs in size. In some patients, the detected copy-number change occurs within a gene known to be causative of the observed clinical phenotype, demonstrating the ability of this array to detect clinically relevant CNVs with subkilobase resolution. In summary, we demonstrate the utility of a custom-designed, exon-targeted oligonucleotide array to detect intragenic copy-number changes in patients with various clinical phenotypes.