Effect of nonsense-mediated mRNA decay factor SMG9 deficiency on premature aging in zebrafish.

SMG9 is an essential component of the nonsense-mediated mRNA decay (NMD) machinery, a quality control mechanism that selectively degrades aberrant transcripts. Mutations in SMG9 are associated with heart and brain malformation syndrome (HBMS). However, the molecular mechanism underlying HBMS remains unclear. We generated smg9 mutant zebrafish (smg9oi7/oi7) that have a lifespan of approximately 6 months or longer, allowing for analysis of the in vivo function of Smg9 in adults in more detail. smg9oi7/oi7 zebrafish display congenital brain abnormalities and reduced cardiac contraction. Additionally, smg9oi7/oi7 zebrafish exhibit a premature aging phenotype. Analysis of NMD target mRNAs shows a trend toward increased mRNA levels in smg9oi7/oi7 zebrafish. Spermidine oxidase (Smox) is increased in smg9oi7/oi7 zebrafish, resulting in the accumulation of byproducts, reactive oxygen species, and acrolein. The accumulation of smox mRNA due to NMD dysregulation caused by Smg9 deficiency leads to increased oxidative stress, resulting in premature aging.

A pH imbalance is linked to autophagic dysregulation of inner ear hair cells in Atp6v1ba-deficient zebrafish.

V-ATPase is an ATP hydrolysis-driven proton pump involved in the acidification of intracellular organelles and systemic acid-base homeostasis through H+ secretion in the renal collecting ducts. V-ATPase dysfunction is associated with hereditary distal renal tubular acidosis (dRTA). ATP6V1B1 encodes the B1 subunit of V-ATPase that is integral to ATP hydrolysis and subsequent H+ transport. Patients with pathogenic ATP6V1B1 mutations often exhibit an early onset of sensorineural hearing loss. However, the mechanisms underlying this association remain unclear. We employed morpholino oligonucleotide-mediated knockdown and CRISPR/Cas9 gene editing to generate Atp6v1ba-deficient (atp6v1ba-/-) zebrafish as an ortholog model for ATP6V1B1. The atp6v1ba-/- zebrafish exhibited systemic acidosis and significantly smaller otoliths compared to wild-type siblings. Moreover, deficiency in Atp6v1ba led to degeneration of inner ear hair cells, with ultrastructural changes indicative of autophagy. Our findings indicate a critical role of ATP6V1B1 in regulating lysosomal pH and autophagy in hair cells, and the results provide insights into the pathophysiology of sensorineural hearing loss in dRTA. Furthermore, this study demonstrates that the atp6v1ba-/- zebrafish model is a valuable tool for further investigation into disease mechanisms and potential therapies for acidosis-related hearing impairment.

Ankle2 deficiency-associated microcephaly and spermatogenesis defects in zebrafish are alleviated by heterozygous deletion of vrk1.

Autosomal recessive primary microcephaly (MCPH) is a rare congenital disorder characterized by a below average brain volume at birth and is associated with neurodevelopmental disorders such as growth retardation and intellectual disability. Mutations in ANKLE2 have been identified as one of the causes of MCPH (MCPH16). ANKLE2 is a target molecule of the Zika virus NS4a protein that interferes with ANKLE2 function, resulting in severe microcephaly. ANKLE2 is essential for organizing the nuclear envelope and chromatin structures during the mitotic-end process via barrier to autointegration factor (BAF) dephosphorylation. However, the precise mechanism by which the loss of ANKLE2 function causes the pathogenesis of microcephaly remains unclear. In this study, we generated Ankle2-deficient zebrafish (ankle2-/-) with a significant reduction in brain size compared with that of their control siblings. The ankle2-/- brain showed a significant decrease in the number of radial glial progenitor cells, suggesting that Ankle2 deficiency in zebrafish causes neurogenesis defects. Furthermore, ankle2-/- male zebrafish showed infertility owing to defects in spermatogenesis. Notably, microcephaly was overcome by vrk1 morpholino knockdown or vrk1 heterozygous deletion. In addition, spermatogenesis in ankle2-/- zebrafish males was partially restored by the vrk1 heterozygous deletion, although infertility was not resolved. These results indicate that ANKLE2 and VRK1 coordinate with each other for BAF phosphorylation to maintain normal mitosis during neurogenesis and spermatogenesis.

Rituximab-induced serum sickness in a girl with nephrotic syndrome.

Rituximab (RTX) has been used to treat B cell lineage lymphoma/leukemia or autoimmune or autoinflammatory disorders. RTX therapy has been extensively applied to cases of frequently relapsing nephrotic syndrome (FRNS) and steroid-dependent nephrotic syndrome. Rituximab-induced serum sickness (RISS) has been recognized as a rare severe type-3 hypersensitivity reaction in patients treated with RTX. We herein report a 10-year-old girl with RISS in FRNS. She was diagnosed with RISS based on characteristic symptoms, such as a fever, rash, arthritis, or proteinuria, during RTX therapy associated with a high level of human anti-chimeric antibody. Even after recovering from acute symptoms by RISS, she suffered from worsening relapses of nephrotic syndrome. The symptoms of RISS are non-specific, resembling viral infections, autoinflammatory diseases and Kawasaki disease, especially in children. While RISS is a rare complication among patients with nephrotic syndrome, it should be carefully considered as a severe complication in patients being treated with RTX.

A case of HDR syndrome coexisting with tetralogy of Fallot, with a novel GATA3 mutation, which manifested as a renal abscess.

HDR syndrome is characterized by the triad of primary hypoparathyroidism, sensorineural hearing loss and renal malformation with widely variable manifestations. It is an autosomal dominant inherited disease caused by a mutation of the GATA3 (NM_001002295.2), which is located on chromosome 10p14. Congenital heart disease, such as tetralogy of Fallot, a typical complication of DiGeorge syndrome, is a rare complication of HDR syndrome. We herein report a case of HDR syndrome coexisting tetralogy of Fallot with a novel mutation, c.964C > T (p.Gln322*). This case suggested that the screening of renal involvement should be carefully performed in patients with a phenotypic combination of hypoparathyroidism and sensorineural hearing loss, to facilitate the early diagnosis of HDR syndrome. In addition, when the deletion of chromosome 22q11.2 is not detected by a fluorescence in situ hybridization analysis in patients exhibiting the partial phenotype of DiGeorge syndrome, the possibility of HDR syndrome should be considered and the renal function should be repeatedly evaluated.

Medical certification reduces the number of children requiring allergen elimination diets for school lunches.

BACKGROUND: Following the increase in the number of children with food allergies, support systems are now required for school lunches, but a large-scale factual investigation has not been carried out. OBJECTIVE: We evaluated the features of elimination diet due to food allergy and the support system in kindergartens and schools. METHODS: A prefecture-based questionnaire survey regarding measures for food allergies in school lunches of all kindergartens, public elementary schools, and public junior high schools (631 facilities) was conducted in Oita Prefecture, Japan. RESULTS: The recovery rate of the questionnaire was 99.5%, which included 106,008 students in total. A total of 1,562 children (1.5%) required elimination diets. The rate of children on elimination diets in kindergartens and elementary/junior high schools that required medical certification by a physician was 1.2% (324 among 27,761 children), which was significantly lower than the 1.8% of children (1,227 among 68,576 students) on elimination diets at the request of guardians without the need for medical certification (p < 0.0001). A total of 43.9% of the kindergartens and schools said that they would contact guardians if symptoms were observed after accidental ingestion, while a low 8.1% stated that they provided support to children themselves, including the administration of adrenaline auto-injectors. CONCLUSION: Medical certification reduces the number of children requiring elimination diets, but it has not been adequately implemented. Furthermore, waiting to contact guardians after symptoms are observed may lead to the delayed treatment of anaphylaxis. Cooperation between physicians and teachers is desired to avoid the overdiagnosis and undertreatment of children with food allergies.

Microarray analysis of 50 patients reveals the critical chromosomal regions responsible for 1p36 deletion syndrome-related complications.

OBJECTIVE: Monosomy 1p36 syndrome is the most commonly observed subtelomeric deletion syndrome. Patients with this syndrome typically have common clinical features, such as intellectual disability, epilepsy, and characteristic craniofacial features. METHOD: In cooperation with academic societies, we analyzed the genomic copy number aberrations using chromosomal microarray testing. Finally, the genotype-phenotype correlation among them was examined. RESULTS: We obtained clinical information of 86 patients who had been diagnosed with chromosomal deletions in the 1p36 region. Among them, blood samples were obtained from 50 patients (15 males and 35 females). The precise deletion regions were successfully genotyped. There were variable deletion patterns: pure terminal deletions in 38 patients (76%), including three cases of mosaicism; unbalanced translocations in seven (14%); and interstitial deletions in five (10%). Craniofacial/skeletal features, neurodevelopmental impairments, and cardiac anomalies were commonly observed in patients, with correlation to deletion sizes. CONCLUSION: The genotype-phenotype correlation analysis narrowed the region responsible for distinctive craniofacial features and intellectual disability into 1.8-2.1 and 1.8-2.2 Mb region, respectively. Patients with deletions larger than 6.2 Mb showed no ambulation, indicating that severe neurodevelopmental prognosis may be modified by haploinsufficiencies of KCNAB2 and CHD5, located at 6.2 Mb away from the telomere. Although the genotype-phenotype correlation for the cardiac abnormalities is unclear, PRDM16, PRKCZ, and RERE may be related to this complication. Our study also revealed that female patients who acquired ambulatory ability were likely to be at risk for obesity.