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PURPOSE: We sought to describe a disorder clinically mimicking cystic fibrosis (CF) and to elucidate its genetic cause. METHODS: Exome/genome sequencing and human phenotype ontology data of nearly 40 000 patients from our Bio/Databank were analysed. RNA sequencing of samples from the nasal mucosa from patients, carriers and controls followed by transcriptome analysis was performed. RESULTS: We identified 13 patients from 9 families with a CF-like phenotype consisting of recurrent lower respiratory infections (13/13), failure to thrive (13/13) and chronic diarrhoea (8/13), with high morbidity and mortality. All patients had biallelic variants in AGR2, (1) two splice-site variants, (2) gene deletion and (3) three missense variants. We confirmed aberrant AGR2 transcripts caused by an intronic variant and complete absence of AGR2 transcripts caused by the large gene deletion, resulting in loss of function (LoF). Furthermore, transcriptome analysis identified significant downregulation of components of the mucociliary machinery (intraciliary transport, cilium organisation), as well as upregulation of immune processes. CONCLUSION: We describe a previously unrecognised autosomal recessive disorder caused by AGR2 variants. AGR2-related disease should be considered as a differential diagnosis in patients presenting a CF-like phenotype. This has implications for the molecular diagnosis and management of these patients. AGR2 LoF is likely the disease mechanism, with consequent impairment of the mucociliary defence machinery. Future studies should aim to establish a better understanding of the disease pathophysiology and to identify potential drug targets.
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Fibrose Cística , Mucoproteínas/genética , Proteínas Oncogênicas/genética , Fibrose Cística/diagnóstico , Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Exoma , Humanos , Mutação , FenótipoRESUMO
Temtamy syndrome is a syndromic form of intellectual disability characterized by ocular involvement, epilepsy and dysgenesis of the corpus callosum. After we initially mapped the disease to C12orf57, we noted a high carrier frequency of an ancient startloss founder mutation [c.1A>G; p.M1?] in our population, and variable phenotypic expressivity in newly identified cases. This study aims to combine 33 previously published patients with 23 who are described here for the first time to further delineate the phenotype of this syndrome. In addition to the known p.M1? founder, we describe four novel homozygous variants, thus increasing the number of Temtamy syndrome-related C12orf57 variants to seven, all but one predicted to be loss of function. While all patients presented with intellectual disability/developmental delay, the frequency of other phenotypic features was variable: 73.2% (41/56) had epilepsy, 63% (34/54) had corpus callosal abnormalities, 14.5% (8/55) had coloboma, and 16.4% (9/55) had microphthalmia. Our analysis also revealed a high frequency of less recognized features such as congenital heart disease (51.4%), and brain white matter abnormalities (38%, 19/50). We conclude that C12orf57 variants should be considered in the etiology of developmental delay/intellectual disability, even when typical syndromic features are lacking, especially in those who trace their ancestry to Saudi Arabia where a founder C12orf57 mutation is among the most common recessive causes of intellectual disability.
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Agenesia do Corpo Caloso/diagnóstico , Coloboma/diagnóstico , Anormalidades Craniofaciais/diagnóstico , Anormalidades do Olho/diagnóstico , Agenesia do Corpo Caloso/epidemiologia , Agenesia do Corpo Caloso/genética , Alelos , Coloboma/epidemiologia , Coloboma/genética , Anormalidades Craniofaciais/epidemiologia , Anormalidades Craniofaciais/genética , Anormalidades do Olho/genética , Fácies , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Imageamento por Ressonância Magnética , Mutação , Fenótipo , PrevalênciaRESUMO
Alstrom's syndrome (AS) is an autosomal recessively inherited multisystemic disorder that falls under the umbrella of ciliopathy. It is characterized by poor vision, hearing impairment, cardiomyopathy, childhood obesity, diabetes mellitus type 2, dyslipidemia, pulmonary, hepatic, and renal failure besides systemic fibrosis. Biallelic pathogenic variants in ALMS1 gene cause AS. Retrospective study (1990-2017) included 12 Saudi patients with AS based on their phenotype, biochemical markers, and genotype. The study was approved by Fisal Specialist Hospital and Research Centre, Riyadh (RAC number 2131129) on October 2, 2012. This study showed clinical and genetic heterogeneity; six patients showed a founder mutation (IVS18-2A > T in exon 19), whereas six others showed private mutations. AS in Saudi Arabia is underdiagnosed probably because of its variable clinical manifestations. We report 12 Saudi patients with AS to enhance the awareness about this syndrome.
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Cowden syndrome (CS) is a rare autosomal dominant genodermatosis disorder. This disease is characterized by the development of several hamartomata lesions in a variety of tissues from all three embryonic layers. The most well-known hamartomata are those of the gastrointestinal system, which represent one of the major criteria for the diagnosis of CS. Yet, the most frequent initial presenting symptom of the disease is thought to be mucocutaneous symptoms such as trichilemmomas, acral keratosis, and oral papilloma. Early diagnosis and management are essential to improving the quality of life for patients with CS as this disorder predisposes them to cancers such as thyroid, breast, gastrointestinal, and endometrial cancers. This report presents a rare case of CS in a Bahraini child who presented with macrocephaly and had numerous intestinal polyposis. Genetic testing using whole exome sequencing confirmed the diagnosis, identifying a pathogenic de novo phosphatase and tensin homolog gene (PTEN) variant (Chr10 NM_000314.8: c.17_18del p.(Lys6Argfs*4)) in a heterozygous state. This variant has been confirmed by Sanger sequencing.
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Infantile-onset multisystem neurologic, endocrine, and pancreatic disease (IMNEPD) is a rare autosomal recessive multisystemic disease with a prevalence of < 1/1â 000â 000. The wide spectrum of symptoms and associated diseases makes the diagnosis of this disease particularly challenging. Here, we report a 12-year-old Bahraini male who presented with the core clinical features of IMNEPD including intellectual disability, global developmental delay, sensorineural hearing loss, endocrine dysfunction, and exocrine pancreatic insufficiency. The diagnosis was confirmed by genetic testing using whole exome sequencing. This is the first reported case of IMNEPD from Bahrain and was found to have a novel homozygous peptidyl-tRNA hydrolase 2 (PTRH2) gene mutation (NM_001015509.2: c.370del p.(Glu124Lysfs*4)). Moreover, we conducted an extensive literature review with an emphasis on the variable clinical spectrum and genotypes of previously reported patients in comparison to our case.
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Johanson-Blizzard syndrome (JBS) is a rare hereditary autosomal recessive disorder caused by a mutation in the ubiquitin protein ligase E3 component n-recognin 1 (UBR1) gene. This syndrome is characterized by the following typical clinical features: hypoplasia or aplasia of the alae nasi, congenital scalp defects, sensorineural hearing loss, hypothyroidism, growth retardation, psychomotor retardation, imperforate anus, genitourinary anomalies, and atypical hair patterns. Here, we describe a case of a 12-year-old girl with JBS of consanguineous parents. During the last trimester of pregnancy, a congenital abnormality affecting the nose was detected. Immediately after birth, the clinical examination revealed dysmorphic features in the form of hypoplastic alae nasi, microcephaly, mild hypotelorism, and cutis aplasia on the scalp. The genetic testing of the patient showed a novel sequence change mutation of the UBR1 gene (1bp duplication causing a frameshift), while both parents were carriers for this mutation. Moreover, a diagnosis of pancreatic insufficiency and subclinical hypothyroidism was made based on clinical presentation and laboratory results. The patient was started on pancreatic enzyme replacement therapy and fat-soluble vitamins, minerals, and antioxidant syrup. Further assessment revealed hypotonia, growth impairment, delay in reaching developmental milestones, and bilateral profound sensorineural hearing loss, which was managed with bilateral cochlear implantation. In addition, the patient underwent multiple craniofacial reconstructive surgeries. This case report highlights the importance of early diagnosis and multidisciplinary care of patients with JBS.
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Cyclin-dependent kinase 13 (CDK13)-related disorder is a rare autosomal dominant disease caused by pathogenic variants in the CDK13 gene. This disorder was found to be related to several clinical features, including structural cardiac anomalies, developmental delay, anomalies of the corpus callosum, and a variety of facial dysmorphisms. In addition, feeding difficulties and neonatal hypotonia might also present. The diagnosis of this disorder is based on molecular genetic testing to detect the causative pathogenic variants. Here, we report a case of a one-year-old girl from Yemen, residing in Bahrain, with a CDK13-related disorder who was found to have an unusual association of abdominal situs inversus along with multiple structural cardiac anomalies, including atrial septal defect, ventricular septal defect, patent ductus arteriosus, interrupted inferior vena cava, bilateral superior vena cava, mild coarctation of the aorta, dilated coronary sinuses, and mild regurgitation in the tricuspid valve. Moreover, facial dysmorphism including medial epicanthal folds, posteriorly rotated ears, and a depressed nasal bridge was also noted. Further assessment showed a delay in reaching developmental milestones, including speech and motor delay. The patient also presented with recurrent episodes of upper respiratory tract infections, acute bronchiolitis, and lobar pneumonia which required admission to the intensive care unit and ventilation. The last infection episode was at the age of one year. Thereafter, the patient underwent cardiac repair of the ventricular septal defect followed by no more infection episodes until the age of one year and two months. The diagnosis of CDK13 was confirmed by a whole exome sequencing test which demonstrated a novel missense variant in exon 14 of the CDK13 gene as a variant of uncertain significance in a heterozygous state.
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This case report is about a 19-month-old boy, product of an in vitro fertilization twin pregnancy and born to young non-consanguineous parents, who presented with speech and motor developmental delay. On genetic evaluation, he was found to have the exceedingly rare variant 49, XXXYY of Klinefelter syndrome. Given the rarity of this condition and the limited literature available, this case report will surely add value to the literature.
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Bile acid synthesis disorders (BASD) are a group of rare autosomal recessive disorders. Of the nine different versions, BASD type 4 is characterized by a gene mutation in alpha-methylacyl-CoA racemase (AMACR), which is located on chromosome 5p13. These disorders generally present with a normal gamma-glutamyl transferase with cholestasis, absence of pruritis, and malabsorption of fat, which can lead to fat-soluble vitamin deficiencies. In adulthood, patients usually develop neurological sequelae. Initial testing can be done through the measurement of urine metabolites; however, confirmation of the diagnosis is achieved through whole exome sequencing. Treatment involves supplementation of oral cholic acid and modification of diet. Only 23 patients with this disease have been described. Here, we report two cases of siblings from a family in Bahrain with a novel AMACR mutation and a unique association with autoimmune antibodies alongside a literature review.
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Primary ciliary dyskinesia (PCD) is a rare autosomal recessive genetic disorder. It is caused by a defect in the action of the cilia lining multiple organs of the body, including the lungs, the sinuses, hepatobiliary and reproductive organs. In general, the estimated prevalence of this condition is one in 15,000-20,000 individuals. It is characterized by the triad of chronic sinusitis, bronchiectasis, and situs inversus, which occurs in 50% of the cases. It can be associated with other diseases too. Genetic studies can aid in confirming the diagnosis of this condition. A high degree of suspicion about PCD among pediatricians, neonatologists, otorhinolaryngologists, and pulmonologists is essential to make early referrals of patients before they develop irreversible lung damage. Hence, early diagnosis and appropriate treatment are very important. Multicenter collaborations might improve the quality of treatment and patient outcomes. Here, we discuss a case of PCD with a unique association with type IIIb jejunal atresia, and developmental delay secondary to vitamin B12 deficiency. Moreover, the patient was found to have a novel DNAH9 gene mutation in a compound heterozygous state. This is the first case of this rare disease to be reported from Bahrain. This case report is also associated with an extensive literature review.