Journal Article

A 73,128 bp de novo deletion encompassing the OPN1LW/OPN1MW gene cluster in sporadic Blue Cone Monochromacy: a case report

Kohl, Susanne, Buena-Atienza, Elena, Wissinger, Bernd, Nasser, Fadi

2018

Overview

Background Blue Cone Monochromacy (BCM) is a rare congenital cone dysfunction disorder with X-linked recessive mode of inheritance. BCM is caused by mutations at the OPN1LW/MW cone opsin gene cluster including deletions of the locus control region (LCR) and/or parts of the gene cluster. We aimed at investigating the clinical presentation, genetic cause and inheritance underlying a sporadic case of BCM. Case presentation We report a 24-year-old male presenting with congenital photophobia, nystagmus and colour vision abnormalities. There was no history of retinal dystrophy in the family. Clinical diagnosis of BCM was supported by genetic investigations of the patient and his family members. Molecular genetic analysis of the OPN1LW/OPN1MW gene cluster revealed a novel deletion of about 73 kb in the patient encompassing the LCR. The deletion was absent in the X-chromosomes of both the mother and transmitting grandfather. Conclusions The present report provides the clinical findings and the genetic basis underlying a sporadic BCM case which is caused by a de novo deletion within the OPN1LW/MW gene cluster originating from the mother’s germline due to Alu-repeat mediated recombination. This is the first report of a de novo deletion resulting in BCM, highlighting the importance to consider BCM and perform genetic testing for this condition in male patients with cone dysfunction also in the absence of a positive family history.

• Publisher: BioMed Central,BioMed Central Ltd,BMC
• Subject: Adult / Age / Alu-mediated recombination / Biomedical and Life Sciences / Biomedicine / Blue Cone Monochromacy / Case Report / Case reports / Case studies / Chromosome deletion / Chromosomes, Human, X - genetics / Clinical-Molecular Genetics and Cytogenetics / Color / Color vision / Color Vision Defects - genetics / Colour vision deficiency / Cytogenetics / De novo mutations / Diagnosis / Families & family life / Gene deletion / Gene Function / Gene mutation / Genes / Genetic analysis / Genetic aspects / Genetic screening / Genotype & phenotype / Hereditary diseases / Heredity / Human Genetics / Humans / Male / Multigene Family - genetics / Mutation / MW gene / Myopia / Nystagmus / Patients / Pedigree / Photoreceptors / Recombination / Retina / Retinal degeneration / Retinal dystrophy / Rod Opsins - genetics / Sequence Deletion - genetics / Sporadic cases / Testing laboratories / Vision disorders / Young Adult