North Carolina Macular Dystrophy Is Caused by Dysregulation of the Retinal Transcription Factor PRDM13.
OBJECTIVE
To identify specific mutations causing North Carolina macular dystrophy (NCMD).


METHODS
Whole-genome sequencing coupled with reverse transcription polymerase chain reaction (RT-PCR) analysis of gene expression in human retinal cells.


METHODS
A total of 141 members of 12 families with NCMD and 261 unrelated control individuals.


METHODS
Genome sequencing was performed on 8 affected individuals from 3 families affected with chromosome 6-linked NCMD (MCDR1) and 2 individuals affected with chromosome 5-linked NCMD (MCDR3). Variants observed in the MCDR1 locus with frequencies <1% in published databases were confirmed using Sanger sequencing. Confirmed variants absent from all published databases were sought in 8 additional MCDR1 families and 261 controls. The RT-PCR analysis of selected genes was performed in stem cell-derived human retinal cells.


METHODS
Co-segregation of rare genetic variants with disease phenotype.


RESULTS
Five sequenced individuals with MCDR1-linked NCMD shared a haplotype of 14 rare variants spanning 1 Mb of the disease-causing allele. One of these variants (V1) was absent from all published databases and all 261 controls, but was found in 5 additional NCMD kindreds. This variant lies in a DNase 1 hypersensitivity site (DHS) upstream of both the PRDM13 and CCNC genes. Sanger sequencing of 1 kb centered on V1 was performed in the remaining 4 NCMD probands, and 2 additional novel single nucleotide variants (V2 in 3 families and V3 in 1 family) were identified in the DHS within 134 bp of the location of V1. A complete duplication of the PRDM13 gene was also discovered in a single family (V4). The RT-PCR analysis of PRDM13 expression in developing retinal cells revealed marked developmental regulation. Next-generation sequencing of 2 individuals with MCDR3-linked NCMD revealed a 900-kb duplication that included the entire IRX1 gene (V5). The 5 mutations V1 to V5 segregated perfectly in the 102 affected and 39 unaffected members of the 12 NCMD families.


CONCLUSIONS
We identified 5 rare mutations, each capable of arresting human macular development. Four of these strongly implicate the involvement of PRDM13 in macular development, whereas the pathophysiologic mechanism of the fifth remains unknown but may involve the developmental dysregulation of IRX1.
Molecular Insight Research Foundation, Glendale, California.
Kent W
KW
Small
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Adam P
AP
DeLuca
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
S Scott
SS
Whitmore
National Eye Clinic, Kennedy Center, Glostrup, Denmark, and Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
Thomas
T
Rosenberg
Molecular Insight Research Foundation, Glendale, California.
Rosemary
R
Silva-Garcia
Molecular Insight Research Foundation, Glendale, California.
Nitin
N
Udar
Service d'Exploration de la vision et Neuro-ophtalmologie CHRU, Lille, France.
Bernard
B
Puech
University of Texas Health Science Center at Houston, Houston, Texas.
Charles A
CA
Garcia
Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California.
Thomas A
TA
Rice
The Pangere Center for Inherited Retinal Diseases, The Chicago Lighthouse for People Who Are Blind or Visually Impaired, Chicago, Illinois.
Gerald A
GA
Fishman
Department of Ophthalmology and Vision Sciences, Programme of Genetics and Genomic Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Elise
E
Héon
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
James C
JC
Folk
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Luan M
LM
Streb
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Christine M
CM
Haas
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Luke A
LA
Wiley
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Todd E
TE
Scheetz
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
John H
JH
Fingert
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Robert F
RF
Mullins
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa.
Budd A
BA
Tucker
Department of Ophthalmology and Visual Sciences, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa. Electronic address: edwin-stone@uiowa.edu.
Edwin M
EM
Stone
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics*; D003317:Corneal Dystrophies, Hereditary / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D005190:Family; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D008040:Genetic Linkage; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D010375:Pedigree; D010641:Phenotype; D011110:Polymorphism, Genetic; D012313:RNA / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D041623:Tomography, Optical Coherence; D055815:Young Adult
D005136:Eye Proteins; C402686:MCDR1 protein, human; D012313:RNA