Background: Congenital hypothyroidism (CH) is the most common neonatal metabolic disorder. In patients with CH in China, thyroid dyshormonogenesis is more common than thyroid dysgenesis; however, the genetic causes of CH due to thyroid dyshormonogenesis remain largely unknown. Therefore, we aimed at identifying novel candidate causative genes for CH. Methods: To identify novel CH candidate genes, a total of 599 patients with CH were enrolled and next-generation sequencing was performed. The functions of the identified variants were confirmed using HEK293T and FTC-133 cell lines in vitro and in a mouse model organism in vivo . Results: Three pathogenic contactin 6 ( CNTN6 ) variants were identified in two patients with CH. Pedigree analysis showed that CH caused by CNTN6 variants was inherited in an autosomal recessive pattern. The CNTN6 gene was highly expressed in the thyroid in humans and mice. Cntn6 knockout mice presented with thyroid dyshormonogenesis and CH due to the decreased expression of crucial genes for thyroid hormone biosynthesis ( Slc5a5 , Tpo , and Duox2 ). All three CNTN6 variants resulted in the blocking of the release of the Notch intracellular domain, which could not translocate into the nucleus, impaired NOTCH1 transcriptional activity, and decreased expression of SLC5A5 , TPO , and DUOX2 . Further, we found that DTX1 was required for CNTN6 to promote thyroid hormone biosynthesis through Notch signaling. Conclusions: This study demonstrated that CNTN6 is a novel causative gene for CH through the mediation of thyroid hormone biosynthesis via Notch signaling, which provides new insights into the genetic background and mechanisms involved in CH and thyroid dyshormonogenesis.

Background: In several countries, thyroid dyshormonogenesis is more common than thyroid dysgenesis in patients with congenital hypothyroidism (CH). However, known pathogenic genes are limited to those directly involved in hormone biosynthesis. The aetiology and pathogenesis of thyroid dyshormonogenesis remain unknown in many patients. Methods: To identify additional candidate pathogenetic genes, we performed next-generation sequencing in 538 patients with CH and then confirmed the functions of the identified genes in vitro using HEK293T and Nthy-ori 3.1 cells, and in vivo using zebrafish and mouse model organisms. Results: We identified one pathogenic MAML2 variant and two pathogenic MAMLD1 variants that downregulated canonical Notch signalling in three patients with CH. Zebrafish and mice treated with N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butylester, a γ-secretase inhibitor exhibited clinical manifestations of hypothyroidism and thyroid dyshormonogenesis. Through organoid culture of primary mouse thyroid cells and transcriptome sequencing, we demonstrated that Notch signalling within thyroid cells directly affects thyroid hormone biosynthesis rather than follicular formation. Additionally, these three variants blocked the expression of genes associated with thyroid hormone biosynthesis, which was restored by HES1 expression. The MAML2 variant exerted a dominant-negative effect on both the canonical pathway and thyroid hormone biosynthesis. MAMLD1 also regulated hormone biosynthesis through the expression of HES3, the target gene of the non-canonical pathway. Conclusions: This study identified three mastermind-like family gene variants in CH and revealed that both canonical and non-canonical Notch signalling affected thyroid hormone biosynthesis.

Pediatricians commonly use the complete blood count (CBC) of capillary blood to evaluate health status, guide diagnoses, and determine treatment strategies. This study aimed to establish sex- and age-specific reference intervals (RIs) for 23 capillary CBC parameters for urban preschoolers in Fuzhou, Southeast China. Capillary blood CBC data of 18,369 healthy preschoolers who underwent annual physical examinations at Fujian Maternity and Child Health Hospital between January 01, 2022, and November 31, 2023, were analyzed retrospectively. To fully validate the new RIs, the data of all apparently healthy children within the same age cohort at the same institution were comprehensively analyzed in December 2023. The new RIs were assessed by comparing them with the RIs currently used in laboratories and those obtained from different regions, sample types, or methodologies. Dynamic temporal changes that differ between males and females were observed in the blood system of 3-7-year-old children in this region. The new sex- and age-specific RIs for capillary CBC parameters were feasible to guide clinical decision-making in the local region. Our findings demonstrated the importance of establishing sex- and age-specific RIs for each region and underscored the necessity of continuous adjustment of clinical Rls based on statistical rules and clinical responses.

Sepsis remains a leading cause of morbidity and mortality in neonatal and pediatric intensive care units (NICU/PICU). Given the rapid clinical deterioratio

Human metapneumovirus (hMPV) is a significant pathogen of acute respiratory infection in children. While previous studies have relied on conventional diagnostics that underestimate complex polymicrobial interactions, this study aimed to utilize targeted next-generation sequencing (tNGS) to comprehensively profile the dynamics of its co-colonization or co-infection pathogen spectrum and their impact on disease severity, thereby informing clinical risk stratification. This retrospective study enrolled 526 hospitalized children with hMPV infection. Targeted next-generation sequencing (tNGS) was used to comprehensively analyze the co-colonization or co-infection spectrum stratified by age, gender, sample origin, immune deficiency, and immunization status. Multivariable logistic regression was employed to assess independent associations with host factors and severe clinical outcomes (ICU [intensive care unit] admission, mechanical ventilation, septic shock, pneumonia on imaging). The median age of the inpatients was 36 months, and 15.6% required ICU admission. The overall prevalence of co-detection among the cohort was 100% since we identified at least one pathogen in the existing results from tNGS. The co-colonization or co-infection pathogen spectrum demonstrated significant age specificity, temporal dynamics, and sample type dependency. Multivariable analysis identified several pathogens independently associated with severe outcomes. Specifically, opportunistic and atypical pathogens (such as Cytomegalovirus [prevalence: 7.22%], Herpes Simplex Virus type 1 [1.71%], Klebsiella aerogenes [0.76%], and Tropheryma whipplei [1.90%]) were strong risk factors for ICU admission, invasive ventilation, and septic shock (adjusted Odds Ratios [aOR] ranging from 4.57 to 28.69). Conversely, Fusobacterium nucleatum (25.67%) consistently exhibited a protective effect (eg, aOR=0.43 for ICU admission). Mycoplasma pneumoniae (12.93%) was an independent risk factor for pneumonia on imaging (aOR=2.25), while Human RSV A (1.14%) showed a significant protective association (aOR=0.09). Despite limitations including a single-center retrospective design and the absence of an hMPV-negative control group, the co-colonization or co-infection pathogen spectrum in children with hMPV infection is complex and closely related to host characteristics. Early identification of high-risk co-pathogens (eg, CMV or K. aerogenes) via tNGS should trigger intensified clinical monitoring. Future prospective controlled studies are needed to validate these findings and confirm causality.