title: Mutation analysis of the VMD2 gene in thai families with best macular dystrophy.
abstract: BACKGROUND
  To identify genetic mutations of the VMD2 gene in two Thai families with Best macular dystrophy.
  
  
  METHODS
  Ophthalmic examination including best-corrected visual acuity (BCVA), dilated fundus examination and fundus photography, and electro-oculography (EOG) was performed in two probands and their family members. Mutation screening of the VMD2 gene was performed by single-strand conformation polymorphism (SSCP) analysis followed by direct DNA sequencing of the abnormal exons.
  
  
  RESULTS
  The 58-year-old male proband demonstrated typical egg yolk-like macular lesion in both eyes. Mutational screening of VMD2 identified a band shift in exon 7, which was confirmed by direct DNA sequencing to be a G to A transition at position 724 bp. This novel missense mutation resulted in the change of an amino acid valine to methionine and was responsible for the abnormal Arden ratio in the proband's daughter. The second male proband age 25 had a characteristic egg yolk-like macular lesion in the left eye and a scrambled egg appearance in the right. Mutation analysis identified a C to T transition at position 652 bp in exon 6. This reported missense mutation led to an amino acid substitution of cysteine for arginine. The mutation was documented in the maternal grandmother, the mother, as well as the elder sister of the proband.
  
  
  CONCLUSIONS
  The Val-242-Met mutation is associated with a late-onset visual disturbance and the Arg-218-Cys mutation was associated with marked intra-familial clinical variability of expression. Presymptomatic testing will be available to the family members at risk with high accuracy.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital Mahidol University, Bangkok, Thailand. atchanee@hotmail.com
authors.forename: La-ongsri
authors.initials: LO
authors.lastname: Atchaneeyasakul
authors.forename: Worapoj
authors.initials: W
authors.lastname: Jinda
authors.forename: Natta
authors.initials: N
authors.lastname: Sakolsatayadorn
authors.forename: Adisak
authors.initials: A
authors.lastname: Trinavarat
authors.forename: Ngamkae
authors.initials: N
authors.lastname: Ruangvoravate
authors.forename: Nualanong
authors.initials: N
authors.lastname: Thanasombatskul
authors.forename: Wanna
authors.initials: W
authors.lastname: Thongnoppakhun
authors.forename: Chanin
authors.initials: C
authors.lastname: Limwongse