A novel OPA3 mutation revealed by exome sequencing: An example of reverse phenotyping

Beenish Arif, Kishore R. Kumar, Philip Seibler, Franca Vulinovic, Amara Fatima, Susen Winkler, Gudrun Nürnberg, Holger Thiele, Peter Nürnberg, Ahmad Zeeshan Jamil, Anne Brüggemann, Ghazanfar Abbas, Christine Klein*, Sadaf Naz, Katja Lohmann

*Corresponding author for this work
14 Citations (Scopus)


Importance: We sought to unravel the genetic cause in a consanguineous Pakistani family with a complex neurological phenotype. Observations: Neurological and ophthalmological examination, including videotaping and fundoscopy, and genetic investigations, including homozygosity mapping and exome sequencing, were performed at the University of the Punjab and the University of Lübeck. Participants included 2 severely affected cousins from consanguineous parents, 10 of their reportedly unaffected relatives, and 342 Pakistani controls. Motor symptoms in the 2 patients started at the age of 3 to 4 years and included chorea, cerebellar ataxia, dystonia, and pyramidal tract signs. Genome-wide genotyping delineated 2 regions of homozygosity on chromosomes 13q12.11 to 13q12.13 and 19q12 to 19q13.41. Exome sequencing revealed 2 rare, homozygous variants (c.32 T>A [p.L11Q] in OPA3 and c.941 C>G [p.A314G] in TSHZ3) that segregated with the disease. Only the OPA3 variant was absent in the control subjects and predicted to be damaging. Subsequent ophthalmological assessment revealed bilateral optic atrophy in both patients. Conclusions and Relevance: Mutations in OPA3 have been reported in Costeff optic atrophy syndrome. We identify a novel missense mutation in OPA3 as the cause of a complex neurological disorder, expanding the OPA3-linked phenotype by early-onset pyramidal tract signs and marked lower limb dystonia. Investigation of optic atrophy was initiated only after genetic analysis, a phenomenon referred to as reverse phenotyping.

Original languageEnglish
JournalJAMA Neurology
Issue number6
Pages (from-to)783-787
Number of pages5
Publication statusPublished - 01.01.2013


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