Childhood Blindness in Qatar A high incidence of homocystinuria

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Childhood Blindness in QatarA high incidence of
homocystinuria

• Richard Scawn, Dawn Sim, Charles Claoue
• Queens Hospital, Essex, UK

Richard Scawn has received travel sponsorship
from Rayner The authors have no financial
interest in the subject of this e-poster
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Aim and Background

• The aim of our study was to determine the causes
  of childhood blindness in Qatar
• One previous survey of blindness in adults and
  children of Qatar was carried out in 1977 1
• The State of Qatar is an Arab emirate bordered by
  Saudi Arabia and the Persian Gulf.
• With the discovery of oil in the 1940s came large
  changes in the socioeconomic wealth and
  population growth.
• It is estimated that only about 30 of the
  countrys population (gt1.4million), are citizens.
• All Qataris receive free medical care

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Al-Noor Institute, Doha, Qatar

• Qatars only blind school
• Opened in September of 1998
• Provides a free education for citizens and
  residents
• Students with blindness, low vision, and special
  needs

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Methods

• A visiting Ophthalmologist examined all children
  attending the Al-Noor Institute
• The classification method used was that of the
  British Ophthalmological Surveillance Unit (BOSU)
  study 3
• (1) entirely unavoidable/untreatable,
• (2) entirely preventable, or
• (3) potentially treatable
• Outcomes of the consultation were grouped into 7
  categories, including recommendations for
• (1) surgery, (2) further investigations, (3)
  low vision assessment,
• (4) refraction / contact lens / glasses, (5)
  mainstream school,
• (6) blind school(7) blind school with special
  needs

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Results

• 211 children examined

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Genetically-determined and Acquired causes of
blindness
Genetic causes Total () Acquired causes Total ()
Microphthalmia Lebera Amaurosis Retinitis Pigmentosa High Myopia Retinal detachment Congenital Cataracts Homocystinuria Congenital Glaucoma Albinism Congenital nystagmus Cone Dystrophy Squint/Refractive/Ambylopia Congenital Ptosis Corneal Opacities (Genetic) Neurological (Genetic) 18 (11) 17 (10) 5 (3) 13 (8) 8 (5) 14 (8) 41 (19) 17 (10) 4 (2) 5 (3) 2 (1) 10 (6) 1 (1) 17 (10) 7 (4) Corneal Opacities (Acquired) Neurological (Acquired) Retinopathy of Prematurity Squint / Ambylopia Congenital Ptosis Macular Coloboma 5 (12) 13 (30) 13 (30) 10 (23) 1 (2) 1 (2)
Total 168 (79) 43 (21)
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Blindness by BOSU classification
Entirely unavoidable/untreatable 65 (30.8)
Entirely preventable 25 (11.8)
Retinopathy of prematurity Traumatic brain injury Refractive error/Ambylopia 13 1 11
Potentially treatable 121 (57.3)
High Myopia Retinal detachment Congenital Cataracts Homocystinuria Congenital Glaucoma Corneal opacities Cerebral palsy Hydrocephalus 13 8 14 41 17 22 4 2
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Comparison of the causes of blindness with 1977
survey1
Categories 1977 Current Difference ()
Trachoma 36 0.5 -35.6
Infectious diseases 6.1 1.4 -4.7
Retinal disease 15.0 27 12.0
Trauma 23.8 1.4 -22.4
Genetically determined 17.0 79.8 62.6
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Homocystinuria

• Homocystinuria was by far the most common single
  diagnosis.
• In this group further intervention via cataract
  surgery or YAG laser capsulotomy required in 17
  (n7), refraction or low vision assessment was
  needed in 63 (n26).
• A small number of these children (n4, 9.8) had
  visual acuities that would enable them to attend
  mainstream school.

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Discussion

• Homocystinuria incidence
• Western Europe 1 in 20,000-60,000 4
• Norway 1 in 6400
• Qatar 1 in 3125 5
• Original Qatari tribes amount to about 200,000
  people
• Until the beginning of the 20th century the local
  Qatari tribes were genetically isolated, with a
  high level of intermarriage.
• As in other Gulf States today it is still common
  for first- or second-degree cousins to marry6.
  54 in Qatari population7
• Consequent founder effects are responsible for
  the high prevalence and unusual burden of
  inherited disorders in Qatari population8

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Discussion

• There has been a dramatic shift in the leading
  cause of blindness following economic development
  in Qatar
• In our study genetic diseases account for almost
  80
• Improved education, genetic counseling and
  screening programs8 may reduce the future
  incidence of genetically determined causes of
  blindness in Qatar

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References

1. Hosni FA. Survey of major blinding conditions in
   Qatar. Ophthalmologica. 1977 175(4)215-21.
2. Vision for Children. A global overview of
   blindness, childhood and VISION2020 the right to
   sight. World Health Organization (WHO) and the
   International Agency for the Prevention of
   Blindness (IAPB). www.v2020.org. Accessed April
   2009.
3. Durnian JM, Cheeseman R, Kumar A, Raja V, Newman
   W, Chandna A. Eye. Childhood sight impairment a
   10-year picture. 2009 Feb 27.
4. Mudd SH, Levy HL, Kraus JP. Disorders of
   transsulfuration. In Scriver CR, Beaudet AL, Sly
   WS, Valle D, editors. The Metabolic and Molecular
   Bases of Inherited Disease. New York
   McGraw-Hill. 2001 p 2007-56.
5. El-Said MF, Badii R, Bessisso MS, Shahbek N,
   El-Ali MG, El-Marikhie M, El-Zyoid M, Salem MS,
   Bener A, Hoffmann GF, Zschocke J. A common
   mutation in the CBS gene explains a high
   incidence of homocystinuria in the Qatari
   population. Hum Mutat. 2006 27(7)719.
6. Al-Gazali LI, Bener A, Abdulrazzaq YM, Micallef
   R, al-Khayat AI, Gaber T. Consanguineous
   marriages in the United Arab Emirates. J Biosoc
   Sci 1997 29491-7.
7. Bener A, Alali KA.Consanguineous marriage in a
   newly developed country the Qatari population. J
   Biosoc Sci. 2006 38(2)239-46.
8. Lindner M, Abdoh G, Fang-Hoffmann J, Shabeck N,
   Al-Sayrafi M, Al-Janahi M, Ho S, Abdelrahman MO,
   Ben-Omran T, Bener A, Schulze A, Al-Rifai H,
   Al-Thani G, Hoffmann GF. Implementation of
   extended neonatal screening and a metabolic unit
   in the State of Qatar developing and optimizing
   strategies in cooperation with the Neonatal
   Screening Center in Heidelberg. J Inherit Metab
   Dis. 2007 30(4)522-9.