TY  - CHAP
M1  - Book, Section
TI  - Retinitis Pigmentosa and Stationary Night Blindness
A1  - Dryja, Thaddeus P.
A2  - Valle, David L.
A2  - Antonarakis, Stylianos
A2  - Ballabio, Andrea
A2  - Beaudet, Arthur L.
A2  - Mitchell, Grant A.
PY  - 2019
T2  - The Online Metabolic and Molecular Bases of Inherited Disease
AB  - Retinitis  pigmentosa  is  the  name  given  to  a  set  of  heritable  degenerations  of  the  retina.  Patients  with  retinitis  pigmentosa  typically  experience  night  blindness  and  loss  of  the  midperipheral  visual  field  early  in  the  disease.  As  the  disease  progresses,  the  visual  field  is  reduced  to  a  shrinking  island  of  central  vision  (called  tunnel  vision)  and  scattered  patches  of  far  peripheral  vision.  In  many  cases,  all  useful  vision  is  lost  during  middle  age.  In  advanced  cases  and  sometimes  even  in  early  cases,  the  fundus  oculi  exhibits  the  following  features:  thin  retinal  vessels,  a  pale  optic  nerve  head,  and  clumps  of  intraretinal  pigment.  Related  diseases  that  feature  progressive  degeneration  of  the  retina  include  cone-rod  degeneration,  cone  degeneration,  and  macular  degeneration.  In  cone-rod  degeneration,  there  is  early  loss  of  visual  acuity  due  to  a  progressive  panretinal  degeneration  that  in  early  stages  affects  cone  photoreceptors  more  severely  than  rod  photoreceptors.  In  cone  degeneration,  cones  but  not  rods  degenerate.  In  macular  degeneration  (see  Inherited  Macular  Dystrophies  and  Susceptibility  to  Degeneration),  cones  and  rods  degenerate  in  the  macula  but  not  elsewhere  in  the  retina.  Most  forms  of  retinitis  pigmentosa  and  related  retinal  degenerations  affect  only  the  eye,  although  in  a  minority  of  cases  the  retinal  degeneration  is  one  feature  of  a  syndrome  that  includes  other  systemic  abnormalities,  such  as  retinitis  pigmentosa  and  deafness  in  Usher  syndrome.  In  young  patients  with  the  symptom  of  night  blindness,  it  is  important  to  differentiate  retinitis  pigmentosa  from  stationary  night  blindness.  Both  diagnostic  categories  feature  defective  vision  in  dim  light  as  an  early  symptom,  but  in  stationary  night  blindness,  cone  photoreceptors  and  daytime  vision  do  not  deteriorate  substantially  during  the  patient's  lifetime.Measuring  the  retina's  electrical  response  to  flashes  of  light  is  the  best  way  to  distinguish  the  early  stages  of  progressive  retinal  degeneration  such  as  retinitis  pigmentosa  from  nonprogressive  retinal  diseases  such  as  stationary  night  blindness.  This  noninvasive  measurement,  called  the  electroretinogram  (ERG),  can  be  used  to  diagnose  young  patients  with  retinitis  pigmentosa  and  many  other  forms  of  retinal  degeneration  even  before  visual  symptoms  or  funduscopic  abnormalities  are  apparent.The  visual  loss  in  retinitis  pigmentosa  and  related  retinal  degenerations  corresponds  to  the  degeneration  of  photoreceptor  cells  of  the  retina.  Molecular  genetic  and  biochemical  studies  have  revealed  that  the  defects  causing  these  cells  to  die  can  be  placed  into  three  categories  depending  on  the  mutant  gene  in  each  case:  (a)  a  primary  biochemical  defect  inherent  in  the  photoreceptor  cells  (the  rods,  the  cones,  or  both  cell  types),  (b)  a  primary  biochemical  defect  in  neighboring  retinal  cells  such  as  the  retinal  pigment  epithelium,  or  (c)  a  peculiar  sensitivity  of  the  photoreceptors  or  the  retinal  pigment  epithelium  to  a  generalized  metabolic  defect.  In  stationary  night  blindness,  rod  photoreceptors  malfunction  because  of  defects  inherent  in  them  or  perhaps  in  the  cells  they  synapse  with;  however,  the  rod  or  cone  photoreceptors  do  not  degenerate  at  a  rate  symptomatically  faster  than  that  which  accompanies  normal  aging.Families  with  retinitis  pigmentosa,  cone-rod  degeneration,  cone  degeneration,  or  stationary  night  blindness  can  demonstrate  any  of  the  known  monogenic  inheritance  patterns:  autosomal  dominant,  autosomal  recessive,  or  ...
SN  - 
PB  - McGraw-Hill Education
CY  - New York, NY
Y2  - 2024/04/19
UR  - ommbid.mhmedical.com/content.aspx?aid=1170117332
ER  -