Dominant stop-loss HNRNPA1 variants in juvenile-onset myopathy.

INTRODUCTION/AIMS: Heterogeneous nuclear ribonucleoprotein A1 is involved in nucleic acid homeostatic functions. The encoding gene HNRNPA1 has been associated with several neuromuscular disorders including an amyotrophic lateral sclerosis-like phenotype, distal hereditary motor neuropathy, multisystem proteinopathy, and various myopathies. We report two unrelated individuals with monoallelic stop loss variants affecting the same codon of HNRNPA1. METHODS: Two individuals with unsolved juvenile-onset myopathy were enrolled under approved institutional protocols. Phenotype data were collected and genetic analyses were performed, including whole-exome sequencing (WES). RESULTS: The two probands (MNOT002-01 and K1440-01) showed a similar onset of slowly progressive extremity and facial weakness in early adolescence. K1440-01 presented with facial weakness, winged scapula, elevated serum creatine kinase (CK) levels, and mild neck weakness. MNOT002-01 also exhibited elevated CK levels along with facial weakness, cardiomyopathy, respiratory dysfunction, pectus excavatum, a mildly rigid spine, and loss of ambulation. On quadriceps muscle biopsy, K1440-01 displayed rounded myofibers, mild variation in fiber diameter, and type 2 fiber hypertrophy, while MNOT002-01 displayed rimmed vacuoles. Monoallelic stop-loss variants in HNRNPA1 were identified for both probands: c.1119A>C p.*373Tyrext*6 (K1440-01) and c.1118A>C p.*373Serext*6 (MNOT002-01) affect the same codon and are both predicted to lead to the addition of six amino acids before termination at an alternative stop codon. DISCUSSION: Both stop-loss variants in our probands are likely pathogenic. Our findings contribute to the disease characterization of pathogenic variants in HNRNPA1. This gene should be screened in clinical diagnostic testing of unsolved cases of sporadic or dominant juvenile-onset myopathy.

Non-Ceruloplasmin Copper Identifies a Subtype of Alzheimer's Disease (CuAD): Characterization of the Cognitive Profile and Case of a CuAD Patient Carrying an RGS7 Stop-Loss Variant.

Alzheimer's disease (AD) is a type of dementia whose cause is incompletely defined. Copper (Cu) involvement in AD etiology was confirmed by a meta-analysis on about 6000 participants, showing that Cu levels were decreased in AD brain specimens, while Cu and non-bound ceruloplasmin Cu (non-Cp Cu) levels were increased in serum/plasma samples. Non-Cp Cu was advocated as a stratification add-on biomarker of a Cu subtype of AD (CuAD subtype). To further circumstantiate this concept, we evaluated non-Cp Cu reliability in classifying subtypes of AD based on the characterization of the cognitive profile. The stratification of the AD patients into normal AD (non-Cp Cu ≤ 1.6 µmol/L) and CuAD (non-Cp Cu > 1.6 µmol/L) showed a significant difference in executive function outcomes, even though patients did not differ in disease duration and severity. Among the Cu-AD patients, a 76-year-old woman showed significantly abnormal levels in the Cu panel and underwent whole exome sequencing. The CuAD patient was detected with possessing the homozygous (c.1486T > C; p.(Ter496Argext*19) stop-loss variant in the RGS7 gene (MIM*602517), which encodes for Regulator of G Protein Signaling 7. Non-Cp Cu as an add-on test in the AD diagnostic pathway can provide relevant information about the underlying pathological processes in subtypes of AD and suggest specific therapeutic options.

De novo stop-loss variants in CLDN11 cause hypomyelinating leukodystrophy.

Claudin-11, a tight junction protein, is indispensable in the formation of the radial component of myelin. Here, we report de novo stop-loss variants in the gene encoding claudin-11, CLDN11, in three unrelated individuals presenting with an early-onset spastic movement disorder, expressive speech disorder and eye abnormalities including hypermetropia. Brain MRI showed a myelin deficit with a discrepancy between T1-weighted and T2-weighted images and some progress in myelination especially involving the central and peripheral white matter. Exome sequencing identified heterozygous stop-loss variants c.622T>C, p.(*208Glnext*39) in two individuals and c.622T>G, p.(*208Gluext*39) in one individual, all occurring de novo. At the RNA level, the variant c.622T>C did not lead to a loss of expression in fibroblasts, indicating this transcript is not subject to nonsense-mediated decay and most likely translated into an extended protein. Extended claudin-11 is predicted to form an alpha helix not incorporated into the cytoplasmic membrane, possibly perturbing its interaction with intracellular proteins. Our observations suggest that stop-loss variants in CLDN11 expand the genetically heterogeneous spectrum of hypomyelinating leukodystrophies.

Novel phenotypic variant in the MYH7 spectrum due to a stop-loss mutation in the C-terminal region: a case report.

BACKGROUND: Defects of the slow myosin heavy chain isoform coding MYH7 gene primarily cause skeletal myopathies including Laing Distal Myopathy, Myosin Storage Myopathy and are also responsible for cardiomyopathies. Scapuloperoneal and limb-girdle muscle weakness, congenital fiber type disproportion, multi-minicore disease were also reported in connection of MYH7. Pathogeneses of the defects in the head and proximal rod region of the protein are well described. However, the C-terminal mutations of the MYH7 gene are less known. Moreover, only two articles describe the phenotypic impact of the elongated mature protein product caused by termination signal loss. CASE PRESENTATION: Here we present a male patient with an unusual phenotypic variant of early-onset and predominant involvement of neck muscles with muscle biopsy indicating myopathy and sarcoplasmic storage material. Cardiomyopathic involvements could not be observed. Sequencing of MYH7 gene revealed a stop-loss mutation on the 3-prime end of the rod region, which causes the elongation of the mature protein. CONCLUSIONS: The elongated protein likely disrupts the functions of the sarcomere by multiple functional abnormalities. This elongation could also affect the thick filament degradation leading to protein deposition and accumulation in the sarcomere, resulting in the severe myopathy of certain axial muscles. The phenotypic expression of the detected novel MYH7 genotype could strengthen and further expand our knowledge about mutations affecting the structure of MyHCI by termination signal loss in the MYH7 gene.

A novel stop-loss mutation in NKX2-2 gene as a cause of neonatal diabetes mellitus: molecular characterization and structural analysis.

AIM: To identify the genetic etiology of neonatal diabetes in an infant and to elucidate the molecular mechanism of the identified mutation underlying the pathogenesis. METHODS: Genetic analysis was carried out by sequencing of known etiological genes associated with NDM. Molecular characterization was performed by constructing a identified mutation in NKX2-2 gene and  functional aspects was tested using transactivation, protein expression, DNA binding, nuclear localization assays. Structural analysis was performed by modeling the NKX2-2 protein structure. RESULTS: A novel homozygous frameshift mutation  c.772delC, p.Q258SFs*59 in the NKX2-2 gene was identified in a patient with neonatal diabetes. Functional studies revealed that this mutation resulted in an elongated protein sequence, affecting DNA binding activity and transcriptional function. Structural analysis suggested alterations in the protein's tertiary structure, likely contributing to its dysfunction. CONCLUSION: This study presents the first report of a stop-loss mutation in the NKX2-2 gene associated with NDM. Our findings emphasize the importance of functional and structural characterization to understand the biological consequences of such mutations. This comprehensive analysis provides insights into the molecular mechanisms underlying NDM and its clinical phenotype, which may aid in better diagnosis and management of patients with similar variants in the future.

ENPP1 homozygous stop-loss variant causing generalized arterial calcifications of infancy: About a severe neonatal clinical case.

Generalized Arterial Calcifications of Infancy (GACI) is an extremely rare autosomal recessive genetic condition, mostly due to pathogenic variations in the ENPP1 gene (GACI1, MIM #208000, ENPP1, MIM #173335). To date 46 likely pathogenic or pathogenic distinct variations in ENPP1 have been described, including nonsense, frameshift, missense, splicing variations, and large deletions. Here we report a case of GACI in a male newborn with a homozygous stop-loss variant in ENPP1 treated in Nancy Regional University Maternity Hospital. Based on proband main clinical signs, clinical exome sequencing was performed and showed a deletion of one nucleotide leading to frameshift and stop-loss (NM_006208.3 (ENPP1):c.2746del,p.(Thr916Hisfs*23)). Clinical presentation is characterized by primary neonatal arterial hypertension resulting in hypertrophic cardiomyopathy decompensated by three cardiogenic shocks and a neonatal deep right sylvian stroke. The child died at 24 days of life. This is the first report of a pathogenic stop-loss variant in ENPP1. It is an opportunity to remind clinicians of GACI disease, a rare and severe etiology in neonates with severe hypertension, and possibility of bisphosphonates therapy.

Some properties of stop-loss moments under biased sampling.

The stop-loss moments have generally been used as useful summary measures for analyzing the data which exceeds specific threshold levels. In many scientific studies, the investigator cannot record the sampling units with equal probability, and in such a scenario, the selected sample units appear with unequal probability, in other words with different weights, which leads to a biased or weighted sampling. In the present study, we examine the usefulness of stop-loss moments in biased sampling. The application of the weighted stop-loss moments in analyzing biased data has been investigated and compared using different empirical estimators through simulated and real data sets.

A novel stop-loss DAX1 variant affecting its protein-interaction with SF1 precedes the adrenal hypoplasia congenital with rare spontaneous precocious puberty and elevated hypothalamic-pituitary-gonadal/adrenal axis responses.

The case study unveils the likely mechanism of a novel stop-loss DAX1 variant preceding the prolonged precocious puberty in the adrenal hypoplasia congenital (AHC) boy. A boy aged five years and nine months initially examined for the primary adrenal insufficiency symptoms. Next-generation sequencing confirmed the X-linked inheritance of a novel stop-loss DAX1 variant: c.1411T>C/p.Ter471Gln associated with AHC in the patient. The patient was subjected to a brief clinical follow-up from 11 to 15.1 years of age. The effect of the mutant-DAX1 variant (p.Ter471Gln) on DAX1-steroidogenic factor 1 (SF1) (protein-protein) interaction was studied by protein-protein docking using the ClusPro-online tool. At 5.9 yrs of age, the patient exhibited precocious puberty with the secondary sexual characteristics of Tanner 2 stage (of 9-14 yrs of age). The patient showed primary adrenal insufficiency with diminished cortisol concentrations at blood serum (25 ng/ml) and urine (3.55 µg/24 h) levels. Upon steroidal exposure, the patient showed normalized serum cortisol levels of 45-61 ng/ml. However, the precocious puberty got prolonged with the increased penis length of 8.5 cm and the bone age of 18 yrs old during the follow-up. The patient showed increased basal serum adrenocorticotropic hormone (110->2000 pg/ml) and follicle-stimulating hormone (18.4-22.3 mIU/ml) concentrations. Following an elevated hypothalamic-pituitary-gonadal axis activity witnessed upon gonarellin stimulation. Protein-protein docking confirmed a weaker interaction between the mutant-DAX1 (p.Ter471Gln) protein and the wild-SF1 protein. Overall, we hypothesize the weakened mutant-DAX1-SF1 (protein-protein) interaction could govern the prolonged precocious puberty augmented with the elevated hypothalamic-pituitary-gonadal/adrenal axis responses via SF1-induced neuronal nitric oxide synthetase activation in the patient.

Effect of a medical subsidy on health service utilization among schoolchildren: A community-based natural experiment in Japan.

Reducing out-of-pocket medical payments for children can reduce financial barriers to healthcare, but may increase health service expenditure. Efficient schemes of patient cost-sharing are needed to address this. We explored the impacts of a medical subsidy for children (MSC), which contained two schemes for cost-sharing of medical expenditure and health service utilization. The first is a monthly stop-loss policy, or caps on out-of-pocket payments, for outpatient/inpatient services; this reduces out-of-pocket payments for those who use greater amounts of health services. The second is a free prescription policy, which eliminates out-of-pocket payments regardless of the amount of drug expenditure. Expansion of the MSC was used as a natural experiment in a Japanese prefecture. We analyzed Japanese National Health Insurance claims data covering April 2013 to January 2017, and found no significant effect of the stop-loss policy on outpatient/inpatient service expenditures, regardless of the children's baseline health status. The free prescription policy, however, significantly increased prescription drug expenditure to 116% in the total sample and 121% among children with good health status, but not among children with poor health status. Increased health expenditure among healthy, low-volume users was found to cause increased overall expenditure. The stop-loss policy for children is potentially efficient because it selectively reduced out-of-pocket payments in high-volume users and did not increase overall expenditure.