Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6.

Heimler syndrome (HS) is a rare recessive disorder characterized by sensorineural hearing loss (SNHL), amelogenesis imperfecta, nail abnormalities, and occasional or late-onset retinal pigmentation. We ascertained eight families affected by HS and, by using a whole-exome sequencing approach, identified biallelic mutations in PEX1 or PEX6 in six of them. Loss-of-function mutations in both genes are known causes of a spectrum of autosomal-recessive peroxisome-biogenesis disorders (PBDs), including Zellweger syndrome. PBDs are characterized by leukodystrophy, hypotonia, SNHL, retinopathy, and skeletal, craniofacial, and liver abnormalities. We demonstrate that each HS-affected family has at least one hypomorphic allele that results in extremely mild peroxisomal dysfunction. Although individuals with HS share some subtle clinical features found in PBDs, the diagnosis was not suggested by routine blood and skin fibroblast analyses used to detect PBDs. In conclusion, our findings define HS as a mild PBD, expanding the pleiotropy of mutations in PEX1 and PEX6.

A targeted next-generation sequencing assay for the molecular diagnosis of genetic disorders with orodental involvement.

BACKGROUND: Orodental diseases include several clinically and genetically heterogeneous disorders that can present in isolation or as part of a genetic syndrome. Due to the vast number of genes implicated in these disorders, establishing a molecular diagnosis can be challenging. We aimed to develop a targeted next-generation sequencing (NGS) assay to diagnose mutations and potentially identify novel genes mutated in this group of disorders. METHODS: We designed an NGS gene panel that targets 585 known and candidate genes in orodental disease. We screened a cohort of 101 unrelated patients without a molecular diagnosis referred to the Reference Centre for Oro-Dental Manifestations of Rare Diseases, Strasbourg, France, for a variety of orodental disorders including isolated and syndromic amelogenesis imperfecta (AI), isolated and syndromic selective tooth agenesis (STHAG), isolated and syndromic dentinogenesis imperfecta, isolated dentin dysplasia, otodental dysplasia and primary failure of tooth eruption. RESULTS: We discovered 21 novel pathogenic variants and identified the causative mutation in 39 unrelated patients in known genes (overall diagnostic rate: 39%). Among the largest subcohorts of patients with isolated AI (50 unrelated patients) and isolated STHAG (21 unrelated patients), we had a definitive diagnosis in 14 (27%) and 15 cases (71%), respectively. Surprisingly, COL17A1 mutations accounted for the majority of autosomal-dominant AI cases. CONCLUSIONS: We have developed a novel targeted NGS assay for the efficient molecular diagnosis of a wide variety of orodental diseases. Furthermore, our panel will contribute to better understanding the contribution of these genes to orodental disease. TRIAL REGISTRATION NUMBERS: NCT01746121 and NCT02397824.

Further evidence for causal FAM20A mutations and first case of amelogenesis imperfecta and gingival hyperplasia syndrome in Morocco: a case report.

BACKGROUND: Amelogenesis imperfecta represents a group of developmental conditions, clinically and genetically heterogeneous, that affect the structure and clinical appearance of enamel. Amelogenesis imperfecta occurred as an isolated trait or as part of a genetic syndrome. Recently, disease-causing mutations in the FAM20A gene were identified, in families with an autosomal recessive syndrome associating amelogenesis imperfecta and gingival fibromatosis. CASE PRESENTATION: We report, the first description of a Moroccan patient with amelogenesis imperfecta and gingival fibromatosis, in whom we performed Sanger sequencing of the entire coding sequence of FAM20A and identified a homozygous mutation in the FAM20A gene (c.34_35delCT), already reported in a family with this syndrome. CONCLUSION: Our finding confirms that the mutations of FAM20A gene are causative for amelogenesis imperfecta and gingival fibromatosis and underlines the recurrent character of the c.34_35delCT in two different ethnic groups.

Novel variant related to SATB2-associated syndrome.

BACKGROUND: SATB2-associated syndrome (SAS) also known as Glass syndrome is characterized by/intellectual disability and/or developmental delay coupled with absent or limited speech development. Other abnormalities can be noticed including craniofacial anomalies such as palatal and dental anomalies, behavioural problems and dysmorphic features. It is associated with pathogenic monoallelic variants of the SATB2 gene known to play a key role in brain, dental and jaw development. As phenotype could be unspecific and progressive, clinical diagnostic is difficult. Therefore, genetic testing is mandatory to confirm the disease. Herein, we report clinical and molecular data of a 13-year-old girl with psychomotor developmental delay and behavioural problems. METHODS AND RESULTS: Next-generation sequencing detected the novel monoallelic frameshift variant SATB2(NM_001172509.2): c.1135del(p.Gln379Lysfs*34). Currently, this variant is classified as likely pathogenic according to the American College of Medical Genetics. Sanger sequencing was used to validate the presence of the detected variant in the patient and confirm de novo character of this latter. CONCLUSION: Through this work, we emphasize the value of next-generation sequencing for a precise molecular diagnosis, an adapted clinical management of patients and an adequate genetic counselling of their families.

Oligodontia and Facial Phenotype Associated with a Rare Syndrome.

Introduction: Oligodontia is a dental abnormality in which the patient is missing teeth. It is a hereditary disorder characterized by agenesis of more than six primary or permanent teeth, excluding the wisdom teeth. Oligodontia is often related with an abnormal size of teeth, conical shape, taurodontism, frequent enamel abnormalities, and delayed eruption. Oligodontia may be clinically isolated or associated with ectodermal dysplasia, a large group of rare diseases, and other syndromes. Patient Information. Dental characteristics of a six-and-a-half-year-old Moroccan boy with oligodontia and in apparent good health were described. Clinical Findings. Three syndromes associated with oligodontia have been discussed. Above all, based on the facial phenotype, Dubowitz syndrome has been retained as the most likely diagnostic hypothesis. This case could be the first reported case described in Morocco, but a thorough examination with genetic analysis must be carried out. Conclusion: Oligodontia could clinically be isolated or associated with ectodermal dysplasia, a large group of rare diseases, and other syndromes.

Resolution of eosinophilic granuloma after minimal intervention. Case report and review of literature.

Langerhans cell histiocytosis (LCH), previously known as histiocytosis X, is a rare, proliferative disorder in which the accumulation of pathologic Langerhans cells leads to local tissue infiltration and destruction. The incidence of LCH is estimated to be one case per 200,000 children per year. The role of the dentist is important in early and accurate evaluation, staging and diagnosis of LCH, because it may mimic more common diseases, such as juvenile periodontitis and osteomyelitis. There are multiple treatment options, but the response is unpredictable. The aim of this paper is to give a short, introductory overview on current diagnostic and treatment strategies for LCH in the oral and maxillofacial region and to present a case of LCH that mimicked juvenile periodontitis and was resolved following extraction of affected teeth. The history, radiological appearance, differential diagnosis, histopathology and treatment options for the patient are discussed.

Novel splice site mutation in CNNM4 gene in a family with Jalili syndrome.

Jalili syndrome is a rare autosomal recessive genetic disease characterized by the association of amelogenesis imperfecta and cone-rod retinal dystrophy. This syndrome is caused by mutations in the CNNM4 gene. Different types of CNNM4 mutations have been reported; missense, nonsense, large deletions, single base insertion, and duplication. We used Sanger sequencing to analyze a large consanguineous family with three siblings affected with Jalili syndrome, suspected clinically after dental and ophthalmological examination. These patients are carrying a novel homozygous mutation in the splice site acceptor of intron 3 (c.1682-1G > C) in the CNNM4 gene. We compare the findings of the present family to those from literature, in order to further delineate Jalili syndrome.

A rare association--amelogenesis imperfecta, platispondyly and bicytopenia: a case report.

INTRODUCTION: Amelogenesis imperfecta is an inherited disease characterized by generalized structural abnormalities of the enamel on all teeth, including both primary and permanent dentition. To the best of our knowledge, this is the first case report of a rare association of amelogenesis imperfecta, platyspondyly, and bicytopenia. CASE PRESENTATION: A 5-year-old Moroccan boy was examined in the Centre for Dental Consultation and Treatment, Faculty of Dentistry, Rabat. He was a child of consanguineous parents (first degree). The child failed to thrive (-4 standard deviation score) and displayed delayed overall development. A dental examination revealed a hypoplastic amelogenesis imperfecta with a bacterial biofilm deposit on tooth surfaces. A complete blood count revealed bicytopenia (normocytic-normochromic anemia with thrombocytopenia). A radiographic examination of the spinal column showed a deviation of the spine in the frontal plane in the form of thoracolumbar scoliosis. The interpedicular distance was not expanded; but a mild platyspondyly exists, especially pronounced in T11 and T12. CONCLUSIONS: No other family members presented amelogenesis imperfecta, bicytopenia, or platyspondyly. The consanguineous marriage suggested an autosomal recessive mode of inheritance. Further studies are necessary to clarify the genetic defect producing this syndrome, and the symptomatic associations of amelogenesis imperfecta, platyspondyly and bicytopenia.