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Dafsari HS, Kawalia A, Sprute R, Karakaya M, Malenica A, Herkenrath P, Nürnberg P, Motameny S, Thiele H, Cirak S. Novel mutations in SLC6A5 with benign course in hyperekplexia. Cold Spring Harb Mol Case Stud 2019; 5:mcs.a004465. [PMID: 31604777 PMCID: PMC6913151 DOI: 10.1101/mcs.a004465] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 09/23/2019] [Indexed: 01/01/2023] Open
Abstract
Infants suffering from life-threatening apnea, stridor, cyanosis, and increased muscle tone may often be misdiagnosed with infantile seizures and inappropriately treated because of lack and delay in genetic diagnosis. Here, we report a patient with increased muscle tone after birth and hypertonic attacks with life-threatening apnea but no epileptiform patterns in EEG recordings. We identified novel compound heterozygous variants in SLC6A5 (NM_004211.4:c.[1429T > C];[1430delC]) by trio whole-exome sequencing, containing a base deletion inherited by the asymptomatic mother leading to a frameshift (c.1430delC, p.Ser477PhefsTer9) and a de novo base exchange leading to an amino acid change (c.1429T > C, p.Ser477Pro). To date, there are four known disease-associated genes for primary hyperekplexia, all of which are involved in the functioning of glycinergic synapses. SLC6A5 encodes the sodium- and chloride-dependent glycine transporter 2 (GlyT2), which recaptures glycine, a major inhibitory transmitter in the brainstem and spinal cord. The diagnosis altered the patient's medical care to his benefit because SLC6A5 mutations with rather benign courses of hyperekplexia may be spared of needless pharmacotherapy. Symptoms eventually decreased in frequency until about once in 2 mo at 2 yr age. We present the first report of halting hyperekplexia episodes by maternal soothing in multiple instances. We highlight the importance of clarifying the genetic diagnosis by rapid next-generation sequencing techniques in this group of infantile apneic attacks with hyperekplexia due to the broad differential diagnoses.
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Affiliation(s)
- Hormos Salimi Dafsari
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany.,Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Amit Kawalia
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, Cologne 50931, Germany
| | - Rosanne Sprute
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany.,Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Mert Karakaya
- Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany.,Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Anna Malenica
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany.,Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Peter Herkenrath
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, Cologne 50931, Germany
| | - Susanne Motameny
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, Cologne 50931, Germany
| | - Holger Thiele
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, Cologne 50931, Germany
| | - Sebahattin Cirak
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany.,Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany.,Center for Rare Diseases, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
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