Inherited Retinal Dystrophies are clinically and genetically heterogeneous disorders affecting the photoreceptors. Although NGS has shown to be helpful for the molecular diagnosis of these conditions, some cases remain unsolved. Among these, several individuals harboured monoallelic variants in a recessive gene, suggesting that a comprehensive screening could improve the overall diagnosis. In order to assess the contribution of non-coding variations in a cohort of 29 patients, 25 of them with monoallelic mutations, we performed targeted NGS. The design comprised the entire genomic sequence of three genes (USH2A, ABCA4 and CEP290), the coding exons of 76 genes and two disease-associated intronic regions in OFD1 and PRPF31. As a result, likely causative mutations (8 novel) were identified in 17 probands (diagnostic rate: 58.62%), including two copy-number variations in USH2A (one deletion of exons 22–55 and one duplication of exons 46–47). Possibly damaging deep-intronic mutations were identified in one family, and another with a monoallelic variant harboured causal mutations in a different locus. In conclusion, due to the high prevalence of carriers of IRD mutations and the results obtained here, sequencing entire genes do not seem to be the approach of choice for detecting the second hit in IRD patients with monoallelic variants.
Background
The “Ex-Utero Intrapartum Treatment” (EXIT) procedure allows to ensure fetal airway before completion of delivery and umbilical cord clamping while keeping uteroplacental circulation. Airway obstruction in fetal oropharyngeal and cervical masses can be life-threatening at birth. In those situations, controlled access to fetal airway performed by a trained multidisciplinary team allows safe airway management, while feto-maternal circulation is preserved. We aim to review the indications and outcome of the EXIT procedure in a case series of fetal cervical and oropharyngeal masses.
Methods
We have carried out a retrospective review of all patients with fetal cervical and oropharyngeal masses who underwent an EXIT procedure between 2008 and 2019. Variables evaluated included indication for EXIT, ultrasound and MRI findings, the need of amnioreduction, gestational age at EXIT, birth weight, complications, operative time, survival rate, pathological findings, and postnatal evolution. Five patients are included in this series. One additional case has already been published.
Results
The diagnosis were cervical teratoma (n = 1), epulis (n = 1) and lymphangioma (n = 3). Polyhydramnios was present in 2 patients, requiring amnioreduction in one of them. Mean gestational age at EXIT was 36–37 weeks (range, 34–38 weeks). Median EXIT time in placental support was 9 min (range, 3–22 min). Access to airway was successfully established in EXIT in all cases. All children born by EXIT are currently healthy and without complications.
Conclusion
The localization and characteristics of the mass, its relationship to the airway, and the presence of polyhydramnios seem to be major factors determining indications for EXIT and clinical outcome.
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