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Volk AE, Hedergott A, Preising M, Rading S, Fricke J, Herkenrath P, Nürnberg P, Altmüller J, von Ameln S, Lorenz B, Neugebauer A, Karsak M, Kubisch C. Biallelic mutations in L-dopachrome tautomerase (DCT) cause infantile nystagmus and oculocutaneous albinism. Hum Genet 2021; 140:1157-1168. [PMID: 33959807 DOI: 10.1007/s00439-021-02285-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/19/2021] [Indexed: 11/26/2022]
Abstract
Infantile nystagmus syndrome (INS) denominates early-onset, involuntary oscillatory eye movements with different etiologies. Nystagmus is also one of the symptoms in oculocutaneus albinism (OCA), a heterogeneous disease mainly caused by defects in melanin synthesis or melanosome biogenesis. Dopachrome tautomerase (DCT, also called TYRP2) together with tyrosinase (TYR) and tyrosin-related protein 1 (TYRP1) is one of the key enzymes in melanin synthesis. Although DCT´s role in pigmentation has been proven in different species, until now only mutations in TYR and TYRP1 have been found in patients with OCA. Detailed ophthalmological and orthoptic investigations identified a consanguineous family with two individuals with isolated infantile nystagmus and one family member with subtle signs of albinism. By whole-exome sequencing and segregation analysis, we identified the missense mutation c.176G > T (p.Gly59Val) in DCT in a homozygous state in all three affected family members. We show that this mutation results in incomplete protein maturation and targeting in vitro compatible with a partial or total loss of function. Subsequent screening of a cohort of patients with OCA (n = 85) and INS (n = 25) revealed two heterozygous truncating mutations, namely c.876C > A (p.Tyr292*) and c.1407G > A (p.Trp469*), in an independent patient with OCA. Taken together, our data suggest that mutations in DCT can cause a phenotypic spectrum ranging from isolated infantile nystagmus to oculocutaneous albinism.
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Affiliation(s)
- Alexander E Volk
- Institute of Human Genetics, University Medical Center Hamburg Eppendorf (UKE), Martinistr. 52, 20246, Hamburg, Germany.
| | - Andrea Hedergott
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, 50931, Cologne, Germany
| | - Markus Preising
- Department of Ophthalmology, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Sebastian Rading
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246, Hamburg, Germany
| | - Julia Fricke
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, 50931, Cologne, Germany
| | - Peter Herkenrath
- Department of Paediatrics, University of Cologne, 50931, Cologne, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics, University of Cologne, 50931, Cologne, Germany
| | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, 50931, Cologne, Germany
| | - Simon von Ameln
- Institute of Human Genetics, University of Ulm, 89081, Ulm, Germany
| | - Birgit Lorenz
- Department of Ophthalmology, Justus-Liebig-University Giessen, 35392, Giessen, Germany
- Department of Ophthalmology, University Hospital of Bonn, 53127, Bonn, Germany
| | - Antje Neugebauer
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, 50931, Cologne, Germany
| | - Meliha Karsak
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246, Hamburg, Germany
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg Eppendorf (UKE), Martinistr. 52, 20246, Hamburg, Germany
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