Clinical and genetic analysis of Indian patients with NDP-related retinopathies
NDP-related retinopathies are a group of X-linked disorders characterized by degenerative and proliferative changes of the neuroretina, occasionally accompanied with varying degrees of mental retardation and sensorineural hearing loss. NDP is the predominant gene associated with NDP-related retinopathies. The purpose of this study was to report the clinical and genetic findings in three unrelated patients diagnosed with NDP-related retinopathies.
The patients underwent complete ophthalmic examination followed by genetic analyses. NDP gene was screened by direct sequencing approach. Targeted resequencing of several other ocular genes was carried out in patient samples that either indicated NDP gene deletion or tested negative for NDP mutation. Gene quantitation analysis was performed using real-time PCR.
The whole NDP gene was deleted in patient I, while a missense NDP mutation, c.205T>C, was identified in patient II, and both had classical Norrie disease ocular phenotype (with no other systemic defects). Patient III who was diagnosed with familial exudative vitreoretinopathy did not show any mutation in the known candidate genes as well as in other ocular genes tested.
The patient with whole NDP gene deletion did not exhibit any apparent extraocular defects (like mental retardation or sensorineural hearing loss) during his first decade of life, and this is considered to be a notable finding. Our study also provides evidence emphasizing the need for genetic testing which could eliminate ambiguities in clinical diagnosis and detect carrier status, thereby aiding the patient and family members during genetic counseling.
KeywordsNDP-related retinopathies Norrie disease FEVR NDP gene Mutation
The authors thank the patients and family members for their cooperation and participation in the study. The authors would like to acknowledge Vision Research Foundation (Ref No. 202-2009-P) and the Department of Biotechnology, Government of India (RGYI scheme; BT/PR15111/GBD/27/322/2011) for funding the study and Mr. Manoj Prabhakar for his contribution toward PCR standardization.
This study was funded by Vision Research Foundation (Ref No. 202-2009-P) and the Department of Biotechnology, Government of India (RGYI scheme; BT/PR15111/GBD/27/322/2011).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee (Vision Research Foundation (Ref No. 202-2009-P)) and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.”
Informed consent was obtained from all the patients/family members who participated in the study.
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