Stepwise genetic approach for the diagnosis of primary ciliary dyskinesia in highly consanguineous populations

BACKGROUND

The American Thoracic Society guidelines for the diagnosis of primary ciliary dyskinesia (PCD) consider the presence of a bi-allelic pathogenic variant confirmatory for the diagnosis of PCD, with genetic testing recommended when other confirmatory diagnostic tests are less accessible. We present our experience with genetic testing as first line with a proposed algorithm for high consanguinity populations.

METHODS

Patients with a suspected diagnosis of PCD underwent genetic testing according to a diagnostic algorithm composed of three steps: (1) patients with a previously known causative familial/Bedouin tribal pathogenic variant completed direct testing for a single variant; (2) if the initial test was negative or there was no known pathogenic variant, a PCD genetic panel was completed; (3) if the panel was negative, whole exome sequencing (WES) was completed.

RESULTS

Since the implementation of the protocol, diagnosis was confirmed by genetic testing in 21 patients. The majority of them were of Bedouin origin (81%) and had a positive history of consanguinity (65%). Nine patients (43%) had a sibling with a confirmed diagnosis. Most patients (15/21, 71%) were diagnosed by direct pathogenic variant testing and the remainder by genetic panel (19%) and WES (10%). Disease-causing variants were found in nine genes, with DNAL1 (24%) and DNAAF3, DNAAF5, ZMYND10 (14% each) as the most prevalent ones.

CONCLUSIONS

In highly consanguineous regions, a stepwise genetic testing approach is recommended. This approach may be particularly useful in areas where the ability to obtain confirmatory diagnostic tests through other modalities is less accessible.

Pediatric thermal epiglottitis: insights from a tertiary center experience

Thermal epiglottitis, a non-infectious cause of epiglottitis, is a rare entity that shares some clinical features with infectious epiglottitis. This study presents 16 years of experience in diagnosing and managing thermal epiglottitis. A retrospective descriptive study in a tertiary center in southern Israel included confirmed cases of thermal epiglottitis in children (0-18 years) between 2004 and 2020 by endoscopy. Of approximately 600,000 pediatric ER admissions between 2004 and 2020, seven children were diagnosed by endoscopy with thermal epiglottitis (mean age 24 months, 71% males). Clinical presentation included stridor, respiratory distress, and drooling. Four children had fever and elevated inflammatory markers at presentation and were treated with systemic antibiotics. All were treated with systemic steroids. The median length of stay in the PICU was five days, and four patients required intubations. All fully recovered without experiencing any sequelae.  Conclusion: Thermal epiglottitis stands as a potential contributor to acute upper airway obstruction. Although it's rarity, it should be discussed in any child with acute upper airway obstruction. It is essential to inquire directly about the accidental intake of hot beverages, particularly in cases lacking fever or elevated inflammatory markers. What is Known: • Thermal epiglottitis is a rare, non-infectious condition sharing clinical features with infectious epiglottitis. • Common presentations include stridor, respiratory distress, and drooling. What is New: • Thermal epiglottitis is a potential contributor to acute upper airway obstruction, urging consideration even in the absence of fever or elevated markers. • Direct inquiry about hot beverage intake for diagnosis is essential for diagnosis.

Nationwide genetic analysis for molecularly unresolved cystic fibrosis patients in a multiethnic society: implications for preconception carrier screening

Background

Preconception carrier screening for cystic fibrosis (CF) is usually performed using ethnically targeted panels of selected mutations. This has been recently challenged by the use of expanded, ethnically indifferent, pan‐population panels. Israel is characterized by genetically heterogeneous populations carrying a wide range of CFTR mutations. To assess the potential of expanding the current Israeli preconception screening program, we sought the subset of molecularly unresolved CF patients listed in the Israeli CF data registry comprising ~650 patients.

Methods

An Israeli nationwide genotyping of 152 CF cases, representing 176 patients lacking molecular diagnosis, was conducted. Molecular analysis included Sanger sequencing for all exons and splice sites, multiplex ligation probe amplification (MLPA), and next‐generation sequencing of the poly‐T/TG tracts.

Results

We identified 54 different mutations, of which only 16 overlapped the 22 mutations included in the Israeli preconception screening program. A total of 29/54 (53.7%) mutations were already listed as CF causing by the CFTR2 database, and only 4/54 (7.4%) were novel. Molecular diagnosis was reached in 78/152 (51.3%) cases. Prenatal diagnosis of 24/78 (30.8%) cases could have been achieved by including all CFTR2‐causing mutations in the Israeli panel.

Conclusions

Our data reveal an overwhelming hidden abundance of CFTR gene mutations suggesting that expanded preconception carrier screening might achieve higher preconception detection rates.

Collecting clinical data in primary ciliary dyskinesia- challenges and opportunities

Rationale: Primary ciliary dyskinesia (PCD) is under diagnosed and underestimated. Most clinical research has used some form of questionnaires to capture data but none has been critically evaluated particularly with respect to its end-user feasibility and utility.

Objective: To critically appraise a clinical data collection questionnaire for PCD used in a large national PCD consortium in order to apply conclusions in future PCD research.

Methods: We describe the development, validation and revision process of a clinical questionnaire for PCD and its evaluation during a national clinical PCD study with respect to data collection and analysis, initial completion rates and user feedback.

Results: 14 centers participating in the consortium successfully completed the revised version of the questionnaire for 173 patients with various completion rates for various items. While content and internal consistency analysis demonstrated validity, there were methodological deficiencies impacting completion rates and end-user utility. These deficiencies were addressed resulting in a more valid questionnaire.

Conclusions: Our experience may be useful for future clinical research in PCD. Based on the feedback collected on the questionnaire through analysis of completion rates, judgmental analysis of the content, and feedback from experts and end users, we suggest a practicable framework for development of similar tools for various future PCD research.

Essential role of carbonic anhydrase XII in secretory gland fluid and HCO3 (-) secretion revealed by disease causing human mutation

KEY POINTS

Fluid and HCO3 (-) secretion is essential for all epithelia; aberrant secretion is associated with several diseases. Carbonic anhydrase XII (CA12) is the key carbonic anhydrase in epithelial fluid and HCO3 (-) secretion and works by activating the ductal Cl(-) -HCO3 (-) exchanger AE2. Delivery of CA12 to salivary glands increases salivation in mice and of the human mutation CA12(E143K) markedly inhibits it. The human mutation CA12(E143K) causes disease due to aberrant CA12 glycosylation, and misfolding resulting in loss of AE2 activity.

ABSTRACT

Aberrant epithelial fluid and HCO3 (-) secretion is associated with many diseases. The activity of HCO3 (-) transporters depends of HCO3 (-) availability that is determined by carbonic anhydrases (CAs). Which CAs are essential for epithelial function is unknown. CA12 stands out since the CA12(E143K) mutation causes salt wasting in sweat and dehydration in humans. Here, we report that expression of CA12 and of CA12(E143K) in mice salivary glands respectively increased and prominently inhibited ductal fluid secretion and salivation in vivo. CA12 markedly increases the activity and is the major HCO3 (-) supplier of ductal Cl(-) -HCO3 (-) exchanger AE2, but not of NBCe1-B. The E143K mutation alters CA12 glycosylation at N28 and N80, resulting in retention of the basolateral CA12 in the ER. Knockdown of AE2 and of CA12 inhibited pancreatic and salivary gland ductal AE2 activity and fluid secretion. Accordingly, patients homozygous for the CA12(E143K) mutation have a dry mouth, dry tongue phenotype. These findings reveal an unsuspected prominent role of CA12 in epithelial function, explain the disease and call for caution in the use of CA12 inhibitors in cancer treatment.

The impact of a national population carrier screening program on cystic fibrosis birth rate and age at diagnosis: Implications for newborn screening

BACKGROUND

Population carrier screening (PCS) has been available in Israel since 1999 and universally subsidized since 2008. We sought to evaluate its impact.

METHODS

A retrospective review of governmental databanks, the national CF registry and CF centers.

RESULTS

CF rate per 100,000 live births has decreased from 14.5 in 1990 to 6 in 2011. From 2004-2011 there were 95 CF births: 22 utilized PCS; 68 (72%) had 2 known CFTR mutations; 37% were pancreatic sufficient. At diagnosis, age was 6 (0-98) months; 53/95 had respiratory symptoms, 41/95 failure to thrive and 19/95 pseudomonas. Thirty-four (36%) were Arabs and 19 (20%) orthodox Jews, compared to 20% and 8% respectively, in the general population.

CONCLUSIONS

PCS markedly reduced CF birth rates with a shift towards milder mutations, but was often avoided for cultural reasons. As children regularly have significant disease at diagnosis, we suggest a balanced approach, utilizing both PCS and newborn screening.

Natural history and clinical manifestations of hyponatremia and hyperchlorhidrosis due to carbonic anhydrase XII deficiency

INTRODUCTION

We identified patients of Bedouin origin with a mutation in carbonic anhydrase XII (CA XII) leading to hyponatremia due to excessive salt loss via sweat.

METHODS

The medical records of patients were reviewed for clinical and laboratory data.

RESULTS

A total of 11 subjects were identified; 7 symptomatic patients presented with hyponatremic dehydration in infancy. Screening of the entire kindred identified 4 asymptomatic individuals with elevated sweat chloride. All symptomatic patients had failure to thrive and moderate-severe hyponatremia (106-124 mmol·l(-1)); 6 had hypochloremia (79-94 mmol·l(-1)). All asymptomatic subjects had normal or near-normal serum sodium and chloride concentrations. Both symptomatic and asymptomatic subjects had normal renal functions and normal cortisol response on low-dose ACTH test. All symptomatic patients were treated by dietary salt, which prevents episodes of hyponatremic dehydration and promotes growth. At follow-up, the chief complaints remained heat intolerance, accumulation of salt precipitates on the face and hyperhidrosis. No evidence for chronic renal, respiratory, gastrointestinal or fertility abnormalities was found.

CONCLUSION

Recognizing this newly described entity and differentiating it from cystic fibrosis and pseudohypoaldosteronism are important. Patients with CA XII mutations should be followed even after early childhood, especially in hot temperatures and intense physical activity.

Primary ciliary dyskinesia caused by homozygous mutation in DNAL1, encoding dynein light chain 1

In primary ciliary dyskinesia (PCD), genetic defects affecting motility of cilia and flagella cause chronic destructive airway disease, randomization of left-right body asymmetry, and, frequently, male infertility. The most frequent defects involve outer and inner dynein arms (ODAs and IDAs) that are large multiprotein complexes responsible for cilia-beat generation and regulation, respectively. Although it has long been suspected that mutations in DNAL1 encoding the ODA light chain1 might cause PCD such mutations were not found. We demonstrate here that a homozygous point mutation in this gene is associated with PCD with absent or markedly shortened ODA. The mutation (NM_031427.3: c.449A>G; p.Asn150Ser) changes the Asn at position150, which is critical for the proper tight turn between the β strand and the α helix of the leucine-rich repeat in the hydrophobic face that connects to the dynein heavy chain. The mutation reduces the stability of the axonemal dynein light chain 1 and damages its interactions with dynein heavy chain and with tubulin. This study adds another important component to understanding the types of mutations that cause PCD and provides clinical information regarding a specific mutation in a gene not yet known to be associated with PCD.

Nonattendance in pediatric pulmonary clinics: an ambulatory survey

BACKGROUND

Nonattendance for scheduled appointments disturbs the effective management of pediatric pulmonary clinics. We hypothesized that the reasons for non-attendance and the necessary solutions might be different in pediatric pulmonary medicine than in other pediatric fields. We therefore investigated the factors associated with nonattendance this field in order to devise a corrective strategy.

METHODS

The effect of age, gender, ethnic origin, waiting time for an appointment and the timing of appointments during the day on nonattendance proportion were assessed. Chi-square tests were used to analyze statistically significant differences of categorical variables. Logistic regression models were used for multivariate analysis.

RESULTS

A total of 1190 pediatric pulmonology clinic visits in a 21 month period were included in the study. The overall proportion of nonattendance was 30.6%. Nonattendance was 23.8% when there was a short waiting time for an appointment (1-7 days) and 36.3% when there was a long waiting time (8 days and above) (p-value < 0.001). Nonattendance was 28.7% between 8 a.m. to 3 p.m. and 37.5% after 3 p.m. (p = 0.007). Jewish rural patients had 15.4% nonattendance, Jewish urban patients had 31.2% nonattendance and Bedouin patients had 32.9% nonattendance (p < 0.004). Age and gender were not significantly associated with nonattendance proportions. A multivariate logistic regression model demonstrated that the waiting time for an appointment, time of the day, and the patients' origin was significantly associated with nonattendance.

CONCLUSION

The factors associated with nonattendance in pediatric pulmonary clinics include the length of waiting time for an appointment, the hour of the appointment within the day and the origin of the patient.

Prevalence of vectors of the spotted fever group Rickettsiae and murine typhus in a Bedouin town in Israel

A survey of the vectors of spotted fever group Rickettsiae and of murine typhus was carried out in Rahat, a Bedouin town in the Negev Desert, where the diseases are endemic. Houses with known cases of spotted fever group Rickettsiae or murine typhus were compared with those without reported clinical cases. A neighboring Jewish community, Lehavim, where no cases of spotted fever group Rickettsiae and murine typhus were reported in recent years, was used as a control. In the houses of patients with spotted fever group Rickettsiae in Rahat, an average of 7.4 times more ticks were found than in control houses. Out of 190 ticks isolated from sheep and goats or caught by flagging in Rahat, 90% were Rhipicephalus sanguineus (Latreille), 7.9% Rhipicephalus turanicus Pomerantzev, and 2.1% were Hyalomma sp. In the houses of patients with murine typhus, three times more rats were caught and, on the average, each rat was infested with 2.2 times more fleas than rats in the control houses. Out of 323 fleas collected from 35 Norwegian rats (Rattus norvegicus Berkenhout), 191 were Xenopsylla cheopis Rothschild and 132 Echidnophaga murina Tiraboschi. Thus, there was a six to seven times higher probability of encountering a tick or flea vector where infections had occurred than in control houses in Rahat. The percentage of rats seropositive to Rickettsia typhi was similar in study and control households (78.3 and 76.2, respectively). In the control settlement, Lehavim, only three Mus musculus L. were caught, which were not infested with ectoparasites and their sera were negative for murine typhus. Out of 10 dogs examined in this settlement, 15 R. sanguineus and eight specimens of the cat flea (Ctenocephalides felis felis Bouché) were isolated. No rats were caught in this settlement. These data indicate that there is a correlation among the density of domestic animals, their ectoparasites, and the incidence of spotted fever group Rickettsiae and murine typhus in Rahat.

Pulmonary function following blastomycosis in childhood

In order to determine the pulmonary outcome following blastomycosis during childhood, we compiled a case series of hospitalized patients from a retrospective review with later recall for pulmonary function testing, coupled with prospective measurements of pulmonary function in three patients, at a tertiary care children's hospital. A convenience sample of five of 17 patients hospitalized with pulmonary blastomycosis, whose mean age at the time of diagnosis was 10.6 +/- 5.5 years, was recalled at a mean of 4.5 +/- 3.5 years after diagnosis. Three patients more recently hospitalized underwent serial pulmonary function testing (PFT) prospectively from as soon after the acute infection as their condition permitted. All but two patients had normal PFT when last seen. The two patients with persistent pulmonary sequelae were among those followed up prospectively and had more severe clinical and radiographic pictures at the outset. Pulmonary function in children who suffered from pulmonary blastomycosis is normal in most patients at follow-up years later. Severe radiographic disease and slow recovery over months portend long-term sequelae.

Persistent diarrhea in a cohort of Israeli Bedouin infants: role of enteric pathogens and family and environmental factors

This study examined the role of enteric pathogens and infant, family, and household characteristics in persistent diarrhea. Bedouin infants from southern Israel were followed from birth to age 18-23 months. During monthly home visits, stool samples were obtained, and feeding practices and history of diarrhea were determined, and at age 3 months, an environmental assessment was done. Diarrhea surveillance was either via a network covering all community health care facilities or via weekly interviews with the mother. None of the enteric pathogens examined, including Cryptosporidium parvum and enteroaggregative Escherichia coli, were associated with persistent diarrhea. In multivariate analyses, age at first diarrheal illness and maternal age and maternal education were independently and significantly associated with the risk of persistent diarrhea. These data suggest that persistent diarrhea is a clinical entity that may be related less to a specific enteric pathogen and more to the health experiences of children and their home environment.

Pleural infection in children

The physiology of pleural liquid formation and stages of pleural effusion are reviewed in this article in our recent experience, only 50% of pleural effusions in hospitalized patients were parapneumonic and only about 7% of these patients could be classified as having an empyema. These findings are in contrast to children 20 to 30 years ago in whom over 40% of parapneumonic effusions were empyemas. Diagnostic approaches are also controversial. The accuracy, sensitivity and specificity of various biochemical tests of pleural fluid have not been assessed in children. It seems reasonable to avoid thoracentesis if the clinician is certain of etiology of the pleural effusion from the history, physical examination, and supporting laboratory data. Treatment is also controversial. Indeed, most patients recover without tube thoracostomy. In our series, only 27% of patients were treated with tube drainage. It is suggested that drainage is necessary to relieve respiratory difficulty or pleuritic pain when effusions are relatively large. The need to drain all empyemas is also a controversial issue both in the child and adult. Clearly, what is needed is a carefully designed multicentered prospective study of pleural effusion in children.

Pleural fluid in hospitalized pediatric patients

We reviewed 105 charts of children who were hospitalized in a major teaching hospital between 1987 and 1993 with a diagnosis of pleural effusion established by radiographic study of the chest. There were 75 males and 30 females; mean age was 7.2 years (range 1 day-18 years). Pleural fluid was secondary to trauma, renal disease, or malignancy in 31.5% of patients. Parapneumonic effusions were found in the majority of patients, 64/105 (61%). However, in only 38 of the 64 patients (59%) was an organism isolated from any source. The most common bacterial organism cultured was Haemophilus influenzae (11 patients), followed by Staphylococcus aureus (seven patients). In five of 38 patients, a viral etiology was diagnosed. Pleural fluid was examined in only 35 patients (34%) and a pathogen found in only five (three bacterial, one Candida, one respiratory syncytial virus). It was possible to classify only 17 cases as exudate (fluid/blood protein ratio > or = 0.5) and six cases as transudate (fluid/blood protein < 0.5). Of 64 patients with suspected pleural fluid secondary to infection, 25 (39%) underwent thoracentesis and only 17 (27%) required tube drainage. This study demonstrates a wide spectrum of etiologies for pleural fluid in children, as well as the reduced use of thoracentesis or chest tube drainage in suspected infection. We speculate that this is probably because of the extensive empiric use of broad-spectrum antibiotics. The biochemical criteria established for adults for distinguishing pleural fluid exudates and transudates need to be studied in children.

Pulmonary blastomycosis in children: findings on chest radiographs

OBJECTIVE

The purpose of this study was to identify characteristic radiographic findings in children with pulmonary blastomycosis.

SUBJECTS AND METHODS

We reviewed the charts and radiographs of 18 children with culture-proven acute pulmonary blastomycosis. The 10 boys and eight girls were from 1 to 16 years old. Sixteen were Native Canadian Indians, and two were white. All available chest radiographs, including those obtained in follow-up after treatment was terminated, were reviewed by a pediatric radiologist. Consolidation was classified by location and extent, and other abnormalities were noted.

RESULTS

Initial chest radiographs showed consolidation in 16 patients. Seven patients had single lobe involvement, most commonly of the left lower lobe. Nine patients had multiple lobe involvement. The left lower lobe was most commonly involved in these cases, but the middle lobe was most severely affected. The upper lobes were involved only in children with multiple lobe disease and were only mildly affected. Cavitation developed in two patients, followed by bronchogenic spread of the disease. Pleural effusions were seen in three patients; two also had rib lesions. Hilar adenopathy developed in two children. Five patients had radiographs available, which had been obtained more than a year after onset, and three of these were abnormal.

CONCLUSION

The most common radiologic finding in children with pulmonary blastomycosis is pulmonary consolidation in one or several lobes, which may undergo cavitation. Lymphadenopathy and pleural effusions are uncommon. Chronic abnormalities may develop.

Bone infection resembling phalangeal microgeodic syndrome in children. A case report

Phalangeal microgeodic syndrome of childhood is a rare condition and is the result of necrosis and repair within the phalanges. The cause is unknown. We present a case in which Brucella melitensis was grown from one of the lesions.

Efficacy of herbal tea preparation in infantile colic

We evaluated the effect of an herbal tea preparation on infantile colic in a prospective double-blind study. The use of tea eliminated the colic in 19 (57%) of 33 infants, whereas placebo was helpful in only 9 (26%) of 35 (p < 0.01). The mean colic score was significantly improved in tea-treated infants. No significant differences were noted between groups regarding number of night wakings.