title: Low vision due to cerebral visual impairment: differentiating between acquired and genetic causes.
abstract: BACKGROUND
  To gain more insight into genetic causes of cerebral visual impairment (CVI) in children and to compare ophthalmological findings between genetic and acquired forms of CVI.
  
  
  METHODS
  The clinical data of 309 individuals (mainly children) with CVI, and a visual acuity ≤ 0.3 were analyzed for etiology and ocular variables. A differentiation was made between acquired and genetic causes. However, in persons with West syndrome or hydrocephalus, it might be impossible to unravel whether CVI is caused by the seizure disorder or increased intracranial pressure or by the underlying disorder (that in itself can be acquired or genetic). In two subgroups, individuals with 'purely' acquired CVI and with 'purely' genetic CVI, the ocular variables (such as strabismus, pale optic disc and visual field defects) were compared.
  
  
  RESULTS
  It was possible to identify a putative cause for CVI in 60% (184/309) of the cohort. In the remaining 40% the etiology could not be determined. A 'purely' acquired cause was identified in 80 of the patients (26%). West syndrome and/or hydrocephalus was identified in 21 patients (7%), and in 17 patients (6%) both an acquired cause and West and/or hydrocephalus was present. In 66 patients (21%) a genetic diagnosis was obtained, of which 38 (12%) had other possible risk factor (acquired, preterm birth, West syndrome or hydrocephalus), making differentiation between acquired and genetic not possible. In the remaining 28 patients (9%) a 'purely' genetic cause was identified.CVI was identified for the first time in several genetic syndromes, such as ATR-X, Mowat-Wilson, and Pitt Hopkins syndrome. In the subgroup with 'purely' acquired causes (N = 80) strabismus (88% versus 64%), pale optic discs (65% versus 27%) and visual field defects (72% versus 30%) could be observed more frequent than in the subgroup with 'purely' genetic disorders (N = 28).
  
  
  CONCLUSIONS
  We conclude that CVI can be part of a genetic syndrome and that abnormal ocular findings are present more frequently in acquired forms of CVI.
authors.forename: Daniëlle G M
authors.initials: DG
authors.lastname: Bosch
authors.forename: F Nienke
authors.initials: FN
authors.lastname: Boonstra
authors.forename: Michèl A A P
authors.initials: MA
authors.lastname: Willemsen
authors.forename: Frans P M
authors.initials: FP
authors.lastname: Cremers
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, P,O, Box 9101, Nijmegen, HB 6500, The Netherlands. Bert.deVries@radboudumc.nl.
authors.forename: Bert B A
authors.initials: BB
authors.lastname: de Vries
mesh_terms: D000293:Adolescent; D019575:Blindness, Cortical / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009422:Nervous System Diseases / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D015354:Vision, Low / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D014792:Visual Acuity; D019987:Persons with Visual Disabilities