Audiological phenotyping evaluation in KBG syndrome: Description of a multicenter review.

OBJECTIVES: Our objective was to reinforce clinical knowledge of hearing impairment in KBG syndrome. KBG syndrome is a rare genetic disorder due to monoallelic pathogenic variations of ANKRD11.The typical phenotype includes facial dysmorphism, costal and spinal malformation and developmental delay. Hearing loss in KBG patients has been reported for many years, but no study has evaluated audiological phenotyping from a clinical and an anatomical point of view. METHODS: This French multicenter study included 32 KBG patients with retrospective collection of data on audiological features, ear imaging and genetic investigations. RESULTS: We identified a typical audiological profil in KBG syndrome: conductive (71%), bilateral (81%), mild to moderate (84%) and stable (69%) hearing loss, with some audiological heterogeneity. Among patients with an abnormality on CT imaging (55%), ossicular chain impairment (67%), fixation of the stapes footplate (33%) and inner-ear malformations (33%) were the most common abnormalities. CONCLUSION: We recommend a complete audiological and radiological evaluation and an ENT-follow up in all patients presenting with KBG Syndrome. Imaging evaluation is necessary to determine the nature of lesions in the middle and inner ear.

Bilateral tympanic myxoma: A CARE case report.

INTRODUCTION: Ear myxoma is a rare benign tumor sometimes located on the pinna and the external auditory meatus, associated with Carney Complex (CNC). However, tympanic membrane myxoma has never been described. We present here a case of bilateral tympanic membrane myxoma, following CARE guidelines. OBSERVATION: A 35-year-old woman presented to our department with right otalgia. Otoscopy showed non-specific bilateral tissular masses in the posterior quadrant of the tympanic membranes, with normal hearing thresholds. CT-scan showed a tissular mass without osteolysis. Right-side resection confirmed the lesion as being a myxoma, ruling out differential diagnoses. The patient was then screened for extra-otologic lesions typically associated with ear myxoma in CNC. Only perilabial lesions similar to lentigos suggested CNC. Cardiac, endocrine and thyroid assessment were normal. Genetic testing for a PKRAR1A gene mutation was negative. DISCUSSION: This is to our knowledge the first reported case of tympanic membrane myxoma. It is of particular interest, being bilateral and showing spontaneous involution of the left lesion over the years. Genetic screening was negative; nevertheless, thorough evaluation is essential due to the life-threatening nature of cardiac myxoma and the frequently associated malignant tumors. Potential new mutations associated with CNC should be considered in the future.

Dermatologic manifestations in paediatric neurofibromatosis type 2: a cross sectional descriptive multicentric study.

BACKGROUND: Neurofibromatosis type 2 (NF2) is characterized by bilateral vestibular schwannoma (VS) more often in adults but a severe paediatric form with multiple neurological tumours is also described. In this population, a early diagnosis is important to prevent the onset of neurological complications but is difficult, particularly without a familial history. Cutaneous manifestations, which may precede VS or neurological tumours by several years, may contribute to an early diagnosis, but specific studies are lacking. The objective of this study was to characterize cutaneous manifestations of NF2 in a paediatric population. RESULTS: This observational, descriptive and multicentric study was conducted from April 2019 to April 2020 in seven academic French hospitals. We included patients ≤ 18 years old who fulfilled the Manchester diagnostic criteria or had a pathogenic mutation identified in the NF2 gene. All patients underwent a dermatological examination guided by a standardized questionnaire. 21 children were included, of whom 20 had at least one skin tumour (mean number 5 ± 4.6 [range 0-15]), which led to a diagnosis in four cases. In the other 17 cases, the diagnosis of NF2 was based on neurosensory complications (n = 10), family screening (n = 4) or ocular signs (n = 3). Before the NF2 diagnosis, 15 children had at least one "undiagnosed" cutaneous tumour that did not lead to a specific management. Patients' dermatological examination also revealed < 6 non specific café au lait macules (n = 15), hypopigmented macules (n = 12) with more than 3 lesions in 4 cases, and purple reticulated macules of the trunk (n = 4). CONCLUSION: Dermatological lesions are frequent and early in children with NF2 but rarely lead to the diagnosis. Cutaneous schwannomas are the most frequent but are often underdiagnosed. Café au lait macules are frequent, but atypical and mostly in small numbers. Multiple hypopigmented macules seem suggestive although inconsistent. The sensitivity of reticulated capillary malformation-like lesions remains to be assessed by further studies.

Combined genetic approaches yield a 48% diagnostic rate in a large cohort of French hearing-impaired patients.

Hearing loss is the most common sensory disorder and because of its high genetic heterogeneity, implementation of Massively Parallel Sequencing (MPS) in diagnostic laboratories is greatly improving the possibilities of offering optimal care to patients. We present the results of a two-year period of molecular diagnosis that included 207 French families referred for non-syndromic hearing loss. Our multi-step strategy involved (i) DFNB1 locus analysis, (ii) MPS of 74 genes, and (iii) additional approaches including Copy Number Variations, in silico analyses, minigene studies coupled when appropriate with complete gene sequencing, and a specific assay for STRC. This comprehensive screening yielded an overall diagnostic rate of 48%, equally distributed between DFNB1 (24%) and the other genes (24%). Pathogenic genotypes were identified in 19 different genes, with a high prevalence of GJB2, STRC, MYO15A, OTOF, TMC1, MYO7A and USH2A. Involvement of an Usher gene was reported in 16% of the genotyped cohort. Four de novo variants were identified. This study highlights the need to develop several molecular approaches for efficient molecular diagnosis of hearing loss, as this is crucial for genetic counselling, audiological rehabilitation and the detection of syndromic forms.

Non-invasive prenatal diagnosis (NIPD) of cystic fibrosis: an optimized protocol using MEMO fluorescent PCR to detect the p.Phe508del mutation.

BACKGROUND: Analysis of cell-free foetal DNA (cff-DNA) in maternal plasma is very promising for early diagnosis of monogenic diseases; in particular, cystic fibrosis (CF). However, NIPD of single-gene disorders has been limited by the availability of suitable technical platforms and the need to set up patient or disease-specific custom-made approaches. METHODS: To make research applications more readily accessible to the clinic, we offer a simple assay combining two independent methods to determine the presence or absence of paternally inherited foetal allele p.Phe508del (the most frequent mutation in CF patients worldwide). The first method detects the presence or absence of a p.Phe508del allele by Mutant Enrichment with 3'-Modified Oligonucleotide PCR coupled to Fragment Length Analysis (MEMO-PCR-FLA). The second method detects the p.Phe508del allele with classical Multiplex Fluorescent PCR including five intragenic and extragenic STR markers of the CFTR locus and a specific SRY sequence. RESULTS: We collected 24 plasma samples from 23 women carrying foetuses at risk for CF and tested each sample using both methods. Our new procedures were successfully applied to 10 couples where fathers carried the p.Phe508del mutation and mothers were carrying a different mutation in the CFTR gene. These simple tests provided clear positive or negative results from the maternal plasma of the pregnant women. We confirmed the presence of cff-DNA in the studied samples by the identification of a tri-allelic DNA profile using a miniSTR kit. All results were correlated with chorionic villus sampling or amniocentesis analyses. CONCLUSIONS: This NIPD approach, easily set up in any clinical laboratory where prenatal diagnosis is routinely performed, offers many advantages over current methods: it is simple, rapid, and cost-effective. It opens up the possibility for testing a large number of couples with offspring at risk for CF.