Abstract: We previously reported that impaired type I IFN activity, due to inborn errors of TLR3- and TLR7-dependent type I interferon (IFN) immunity or to autoantibodies against type I IFN, account for 15–20% of cases of life-threatening COVID-19 in unvaccinated patients. Therefore, the determinants of life-threatening COVID-19 remain to be identified in ~ 80% of cases. Methods We report here a genome-wide rare variant burden association analysis in 3269 unvaccinated patients with life-threatening COVID-19, and 1373 unvaccinated SARS-CoV-2-infected individuals without pneumonia. Among the 928 patients tested for autoantibodies against type I IFN, a quarter (234) were positive and were excluded. Results No gene reached genome-wide significance. Under a recessive model, the most significant gene with at-risk variants was TLR7 , with an OR of 27.68 (95%CI 1.5–528.7, P  = 1.1 × 10 −4 ) for biochemically loss-of-function (bLOF) variants. We replicated the enrichment in rare predicted LOF (pLOF) variants at 13 influenza susceptibility loci involved in TLR3-dependent type I IFN immunity (OR = 3.70[95%CI 1.3–8.2], P  = 2.1 × 10 −4 ). This enrichment was further strengthened by (1) adding the recently reported TYK2 and TLR7 COVID-19 loci, particularly under a recessive model (OR = 19.65[95%CI 2.1–2635.4], P  = 3.4 × 10 −3 ), and (2) considering as pLOF branchpoint variants with potentially strong impacts on splicing among the 15 loci (OR = 4.40[9%CI 2.3–8.4], P  = 7.7 × 10 −8 ). Finally, the patients with pLOF/bLOF variants at these 15 loci were significantly younger (mean age [SD] = 43.3 [20.3] years) than the other patients (56.0 [17.3] years; P  = 1.68 × 10 −5 ). Conclusions Rare variants of TLR3- and TLR7-dependent type I IFN immunity genes can underlie life-threatening COVID-19, particularly with recessive inheritance, in patients under 60 years old.

Abstract: Background. There is a recent trend of a worldwide increase in the incidence of autistic spectrum disorder. Early identification and intervention have proved to be beneficial. The original version of the Checklist for Autism in Toddlers (CHAT) was a simple screening tool for identification of autistic children at 18 months of age in the United Kingdom. Children with an absence of joint attention (including protodeclarative pointing and gaze monitoring) and pretend play at 18 months were at high risk of autism. Section A of the CHAT was a self-administered questionnaire for parents, with 9 yes/no questions addressing the following areas of child development: rough and tumble play, social interest, motor development, social play, pretend play, protoimperative pointing (pointing to ask for something), protodeclarative pointing, functional play, and showing. Section B of the CHAT consisted of 5 items, which were recorded with observation of the children by general practitioners or health visitors. The 5 items addressed the child’s eye contact, ability to follow a point (gaze monitoring), pretend (pretend play), produce a point (protodeclarative pointing), and make a tower of blocks. A 6-year follow-up study of & gt;16 000 children screened with the CHAT at 18 months in the United Kingdom showed a sensitivity of only 0.40 and a specificity of 0.98, with a positive predictive value (PPV) of 0.26. Rescreening using the same instrument at 19 months for those who failed the 18-month screening yielded a higher PPV of 0.75. Therefore, children were likely to have autism if they failed the CHAT at 18 months and failed again at 19 months. It was estimated that consistent failure in 3 key questions (ie, protodeclarative pointing, gaze monitoring, and pretend play) at 18 months indicated an 83.3% risk of having autism. Because of the poor sensitivity of the original CHAT for autism, a Modified Checklist for Autism in Toddlers (M-CHAT), consisting of 23 questions, with 9 questions from the original CHAT and an additional 14 questions addressing core symptoms present among young autistic children, was designed in the United States. The original observational part (ie, section B) was omitted. The M-CHAT was designed as a simple, self-administered, parental questionnaire for use during regular pediatric visits. The more questions children failed, the higher their risk of having autism. Two criteria were used to measure the sensitivity and specificity of M-CHAT. Criterion 1 used any 3 of the 23 questions, and criterion 2 used 2 of the 6 best questions that could be used to discriminate autism from other groups. The sensitivity and specificity for criterion 1 were 0.97 and 0.95 and those for criterion 2 were 0.95 and 0.99, respectively. M-CHAT had a better sensitivity than the original CHAT, because children up to 24 months of age were screened, with the aim of identifying those who might regress between 18 and 24 months. The 6 best questions of the M-CHAT addressed areas of social relatedness (interest in other children and imitation), joint attention (protodeclarative pointing and gaze monitoring), bringing objects to show parents, and responses to calling. Joint attention was addressed in the original CHAT, whereas the other areas were addressed only in the M-CHAT. To date, there has been no study of the application of either the original CHAT or the M-CHAT for Chinese populations. Objectives. CHAT-23 is a new checklist translated into Chinese, combining the M-CHAT (23 questions) with graded scores and section B (observational section) of the CHAT. We aimed to determine whether CHAT-23 could discriminate autism at mental ages of 18 to 24 months for Chinese children and to determine the best combination of questions to identify autism. Methods. A cross-sectional cohort study was performed with 212 children with mental ages of 18 to 24 months. The children were categorized into 2 groups, ie, group 1 (N = 87) (autistic disorder: N = 53; pervasive developmental disorder: N = 33) and group 2 (N = 125) (nonautistic). The checklist included self-administered questionnaires with 23 questions (part A) and direct observations of 5 items by trained investigators (part B). We performed discriminant function analysis to determine the key questions that could best discriminate autism from nonautism. The sensitivity and specificity of CHAT-23 were calculated. Results. We found that 7 key questions, addressing areas of joint attention, pretend play, social relatedness, and social referencing, were identified as discriminative for autism. For part A, failing any 2 of 7 key questions, ie, question 13 (does your child imitate you? [eg, you make a face; will your child imitate it?]), question 5 (does your child ever pretend, for example, to talk on the phone or take care of dolls, or pretend other things?), question 7 (does your child ever use his/her index finger to point, to indicate interest in something?), question 23 (does your child look at your face to check your reaction when faced with something unfamiliar?), question 9 (does your child ever bring objects over to you [parent] to show you something?), question 15 (if you point at a toy across the room, does your child look at it?), and question 2 (does your child take an interest in other children?), yielded sensitivity of 0.931 and specificity of 0.768. Failing any 6 of all 23 questions produced sensitivity of 0.839 and specificity of 0.848. For part B, failing any 2 of 4 items produced sensitivity of 0.736, specificity of 0.912, and PPV of 0.853. The 4 observational items were as follows: item B1: during the appointment, has the child made eye contact with you? item B2: does the child look across to see what you are pointing at? item B3: does the child pretend to pour out tea, drink it, etc?; item B4: does the child point with his/her index finger at the light? Conclusion. We found that integrating the screening questions of the M-CHAT (from the United States) and observational section B of the original CHAT (from the United Kingdom) yielded high sensitivity and specificity in discriminating autism at 18 to 24 months of age for our Chinese cohort. This new screening instrument (CHAT-23) is simple to administer. We found that a 2-stage screening program for autism can offer a cost-effective method for early detection of autism at 18 to 24 months. For CHAT-23, use of both the parental questionnaire and direct observation and use of the criterion of failing any 2 of 7 key questions yielded the highest sensitivity but a relatively lower specificity, whereas use of part B yielded the highest specificity but a lower sensitivity. We recommend identifying the possible positive cases with part A (parental questionnaire) and then proceeding to part B (observation) with trained assessors. The proposed algorithm for screening for autism is as follows. 1) The parents or chief caretakers complete a 23-item questionnaire when their children are 18 to 24 months of age. 2) The parents mail, fax, or hand this 23-item questionnaire to the local child health agency. 3) Clerical staff members check for and score failure, with the criteria of failing any 2 of 7 key questions or failing any 6 of 23 questions; if either criterion is met, then the staff members highlight the medical records of the suspicious cases. 4) Trained child health care professionals observe the children who failed any 2 of 7 key questions or any 6 of 23 questions. These identified patients are observed for 5 minutes for part B of the CHAT-23. 5) Any child who fails any 2 of 4 items requires direct referral to a comprehensive autism evaluation team, for early diagnostic evaluation and early intervention. The high sensitivity and specificity of the criteria observed in our study suggested that CHAT-23 might be used to differentiate children with autism. Additional international collaboration with the use of the CHAT, M-CHAT, and CHAT-23 could provide more prospective epidemiologic data, to establish whether there is a genuine increase in the worldwide incidence of autism.

Abstract: Caspases are a conserved family of cysteine proteases. They play diverse roles in inflammatory responses and apoptotic pathways. Among the caspases is a subgroup whose primary function is to initiate apoptosis. Within their long prodomains, caspases‐2, ‐9 and ‐12 contain a caspase activation and recruitment domain while caspases‐8 and ‐10 bear death effector domains. Activation follows the recruitment of the procaspase molecule via the prodomain to a high molecular mass complex. Despite sharing some common features, other aspects of the biochemistry, substrate specificity, regulation and signaling mechanisms differ between initiator apoptotic caspases. Defects in expression or activity of these caspases are related to certain pathological conditions including neurodegenerative disorders, autoimmune diseases and cancer.

Abstract: Clinical management of shrimp allergy is hampered by the lack of accurate tests. Molecular diagnosis has been shown to more accurately reflect the clinical reactivity but the full spectrum of shrimp allergens and their clinical relevance are yet to be established. We therefore sought to comprehend the allergen repertoire of shrimp, investigate and compare the sensitization pattern and diagnostic value of the allergens in allergic subjects of two distinct populations. Methods Sera were collected from 85 subjects with challenge‐proven or doctor‐diagnosed shrimp allergy in Hong Kong and Thailand. The IgE‐binding proteins of Penaeus monodon were probed by Western blotting and identified by mass spectrometry. Recombinant shrimp allergens were synthesized and analyzed for IgE sensitization by ELISA. Results Ten IgE‐binding proteins were identified, and a comprehensive panel of 11 recombinant shrimp allergens was generated. The major shrimp allergens among Hong Kong subjects were troponin C (Pen m 6) and glycogen phosphorylase (Pen m 14, 47.1%), tropomyosin (Pen m 1, 41.2%) and sarcoplasmic‐calcium binding protein (Pen m 4, 35.3%), while those among Thai subjects were Pen m 1 (68.8%), Pen m 6 (50.0%) and fatty acid‐binding protein (Pen m 13, 37.5%). Component‐based tests yielded significantly higher area under curve values (0.77–0.96) than shrimp extract‐IgE test (0.70–0.75). Yet the best component test differed between populations; Pen m 1‐IgE test added diagnostic value only in the Thai cohort, whereas sensitizations to other components were better predictors of shrimp allergy in Hong Kong patients. Conclusion Pen m 14 was identified as a novel shrimp allergen predictive of challenge outcome. Molecular diagnosis better predicts shrimp allergy than conventional tests, but the relevant component is population dependent.

Abstract: Autosomal inborn errors of type I IFN immunity and autoantibodies against these cytokines underlie at least 10% of critical COVID-19 pneumonia cases. We report very rare, biochemically deleterious X-linked TLR7 variants in 16 unrelated male individuals aged 7 to 71 years (mean, 36.7 years) from a cohort of 1202 male patients aged 0.5 to 99 years (mean, 52.9 years) with unexplained critical COVID-19 pneumonia. None of the 331 asymptomatically or mildly infected male individuals aged 1.3 to 102 years (mean, 38.7 years) tested carry such TLR7 variants ( P = 3.5 × 10 −5 ). The phenotypes of five hemizygous relatives of index cases infected with SARS-CoV-2 include asymptomatic or mild infection ( n = 2) or moderate ( n = 1), severe ( n = 1), or critical ( n = 1) pneumonia. Two patients from a cohort of 262 male patients with severe COVID-19 pneumonia (mean, 51.0 years) are hemizygous for a deleterious TLR7 variant. The cumulative allele frequency for deleterious TLR7 variants in the male general population is 〈 6.5 × 10 −4 . We show that blood B cell lines and myeloid cell subsets from the patients do not respond to TLR7 stimulation, a phenotype rescued by wild-type TLR7 . The patients’ blood plasmacytoid dendritic cells (pDCs) produce low levels of type I IFNs in response to SARS-CoV-2. Overall, X-linked recessive TLR7 deficiency is a highly penetrant genetic etiology of critical COVID-19 pneumonia, in about 1.8% of male patients below the age of 60 years. Human TLR7 and pDCs are essential for protective type I IFN immunity against SARS-CoV-2 in the respiratory tract.

Abstract: Anaphylaxis is a significant health burden in most Western countries, but there are little published data on the incidence and pattern of anaphylaxis in Asia. We aim to determine the incidence rate and pattern of anaphylaxis over the past decade among the pediatric population in Hong Kong. Methods Medical records of patients presenting with allergy‐related symptoms during the period 2010 to 2019 were examined. Pediatric patients aged below 18 years who fulfilled the diagnostic criteria for anaphylaxis laid out by the NIAID/FAAN were analyzed. Incidence rates were calculated using population statistics as the denominator. All information pertaining to the anaphylaxis events and patients’ characteristics was retrieved using standardized data collection forms. Results The overall 10‐year estimated incidence of anaphylaxis was 9.76 per 100,000 person‐years, with a rising trend of anaphylaxis incidence across time. Food‐induced anaphylaxis accounted for the majority of hospital presentations, of which peanut and shellfish were the top food triggers in our population. Majority of anaphylaxis episodes were of Grade 4 severity, and young age was a significant predictor of severe allergic reactions. Half of the anaphylaxis episodes were misdiagnosed and adrenaline was only utilized in 42.2% of cases, of which 9.4% were administered adrenaline prior to hospital arrival. Conclusions An increasing trend of anaphylaxis incidence over the past decade is evident in Hong Kong children, with a discrepantly low accuracy in diagnosis and suboptimal management of anaphylaxis. There is a pressing need to heighten public and physicians’ awareness of the distinctive features of anaphylaxis in the pediatric age‐group.