TY  - CHAP
M1  - Book, Section
TI  - The Glaucomas
A1  - Sheffield, Val C.
A1  - Alward, Wallace L. M.
A1  - Stone, Edwin M.
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  - The  glaucomas  are  a  heterogeneous  group  of  diseases  that  result  in  death  of  the  optic  nerve.  Together,  these  disorders  are  the  leading  cause  of  irreversible  blindness  in  the  world.  The  glaucomas  are  categorized  into  open-angle,  closed-angle,  and  congenital  glaucoma  based  on  the  mechanism  by  which  aqueous  outflow  is  impeded  in  the  anterior  chamber  of  the  eye.  Primary  open-angle  glaucoma  (POAG)  accounts  for  the  vast  majority  of  glaucoma  cases.  Major  risk  factors  for  development  of  this  disorder  are  age,  race,  elevated  intraocular  pressure,  and  family  history.  Genetic  mapping  studies  have  resulted  in  the  identification  of  five  POAG  loci.  A  subset  of  POAG  cases  occurs  at  a  young  age  and  is  known  as  juvenile  onset  primary  open-angle  glaucoma  (JOAG),  (MIM  137750).  This  disorder  was  mapped  to  and  shown  to  be  caused  by  mutations  in  a  gene  (GLC1A,  MIM  137750)  that  codes  for  a  504-amino  acid  protein  known  as  myocilin.  Mutations  in  the  GLC1A  gene  have  been  shown  to  account  for  nearly  all  cases  of  autosomal  dominant  JOAG,  and  3  to  4  percent  of  cases  of  adult  onset  POAG.  Glaucoma  caused  by  GLC1A  mutations  is  inherited  as  an  autosomal  dominant  disorder  with  high  penetrance  and  variable  expressivity.Normal  tension  glaucoma  is  a  subtype  of  POAG  that  is  defined  by  the  presence  of  glaucomatous  optic  nerve  changes  and  visual  field  loss  in  patients  with  normal  intraocular  pressure.  This  disorder  is  thought  to  occur  because  of  polygenic  or  multifactorial  inheritance.  A  locus  (GLC1E)  for  this  disorder  has  been  reported  on  chromosome  10p14-p15  based  on  study  of  a  single  pedigree.Pigmentary  glaucoma  (MIM  600510)  is  a  form  of  open-angle  glaucoma  characterized  by  the  presence  of  dense  black  pigment  in  the  trabecular  meshwork  of  the  eye.  The  formation  of  glaucoma  in  patients  with  this  disorder  is  thought  to  be  secondary  to  the  dispersion  of  melanosomes  from  the  iris  into  the  aqueous  humor,  and  subsequently  into  the  trabecular  meshwork.  Two  loci  thought  to  cause  autosomal  dominant  inheritance  of  pigmentary  glaucoma  have  been  reported.Exfoliative  glaucoma  is  a  common  form  of  open-angle  glaucoma  in  which  increased  intraocular  pressure  is  secondary  to  deposition  of  a  fibrillar  material  throughout  the  anterior  segment  of  the  eye.  This  disorder  is  a  disease  of  the  elderly.  It  has  a  high  incidence  in  some  populations,  including  Scandinavians  and  Navajo  Indians.  No  genetic  loci  have  been  identified  for  this  disorder.Corticosteroids  have  been  well  documented  as  inducing  elevated  intraocular  pressure  in  some  patients.  Susceptibility  to  steroid-induced  glaucoma  appears  to  have  genetic  components.Closed-angle  glaucoma  is  characterized  by  impedance  of  aqueous  humor  outflow  secondary  to  the  iris  being  displaced  over  the  trabecular  meshwork.  This  disorder  can  develop  suddenly  and,  unlike  other  forms  of  glaucoma,  results  in  recognizable  symptoms  including  nausea,  vomiting,  headache,  and  severe  eye  pain.The  developmental  glaucomas  result  from  an  abnormality  of  the  iridocorneal  angle  present  at  birth  that  results  in  decrease  aqueous  outflow  and  increased  intraocular  pressure.  The  developmental  glaucomas  can  occur  as  an  isolated  ocular  abnormality,  in  which  case  it  is  known  as  primary  congenital  glaucoma  (PCG),  or  they  can  occur  in  conjunction  with  a  variety  of  other  ocular  and/or  extraocular  ...
SN  - 
PB  - McGraw-Hill Education
CY  - New York, NY
Y2  - 2024/04/25
UR  - ommbid.mhmedical.com/content.aspx?aid=1184071576
ER  -