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Hajirah Saeed, Charles Bouchard; Familial Corneal Patterns in Pellucid Marginal Degeneration (PMD): Uncovering a Possible Etiology. Invest. Ophthalmol. Vis. Sci. 2013;54(15):882.
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The most common of the non-inflammatory ectatic corneal diseases is keratoconus (KC). Another such disease is PMD. There is controversy over PMD and KC being distinct disease entities versus a continuum of corneal disease sharing the same pathogenetic mechanism of corneal ectasia. After our case report of a possible hereditary component in PMD last year, we developed a protocol to prospectively study the clinical signs, disease progression, and possible hereditary patterns of PMD in patients and their family members. As such, the purpose of this study is to assess tomographic and topographic signs of PMD in patients with an established diagnosis of PMD as well as their family members, and to investigate the possible genetic origins of PMD via whole exome sequencing.
Five patients with a diagnosis of PMD as well as their first-degree relatives underwent Pentacam imaging. A total of 14 participants were included in this study. Pentacam imaging was evaluated for abnormalities using the Belin-Ambrosio enhanced ectasia display. Participants also had blood drawn for subsequent genetic analysis via whole exome sequencing. Other variables that were assessed included history of allergies and eye rubbing.
Two of the five families had members other than the proband who demonstrated abnormal imaging. Two of these family members demonstrated clinical signs of disease requiring surgical or other intervention. Four of the five probands had a history of vigorous eye rubbing. Three out of five had environmental allergies. It was also noted that four of the five families that participated had a member with a developmental disability. Whole exome sequencing of blood obtained on all participants was pending at the time of this submission.
This study illustrates a possible hereditary component to PMD and warrants further investigation. Environmental influences as allergies and eye rubbing seem to be significant variables in PMD. Genetic analysis of blood samples from both probands and their family members will help to elucidate any genetic component as well. This analysis via whole exome sequencing is currently in process. The incidence of developmental disabilities in the family members of patients with PMD also warrants further investigation. In sequencing DNA we hope to determine what link, if any, exists between PMD and certain developmental abnormalities.
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