Date Posted: 04 May 2010
Clinicians and researchers from New York's Columbia University have reported the delivery of a healthy baby girl following the first use of pre-implantation genetic diagnosis for the screening of at risk embryos for Stargardt's disease. The newborn's parents had sought genetic counselling and had been tested resulting in confirmation that the father carried 2 ABCA4 mutations while the mother carried 1 potentially pathogenic ABCA4 mutation. The estimated incidence of the disease is 1/10,000. Without pre-implantation genetic diagnosis and IVF treatment the risk for the couple of having a child with Stargardts would have been 50%.
DNA obtained from 15 embryos underwent PCR amplification. Six were shown to have 1 paternal and 1 maternal allele and therefore were labelled as affected with Stargardts while three were inconclusive and six were identified as having normal (unaffected) maternal alleles. Of the six unaffected, two were cryopreserved, three were discarded and one was transferred to the mother's uterus resulting in a singleton pregnancy. Chorionic villus sampling was performed at 11 weeks gestation from which DNA analysis showed that the foetus, as expected, was a carrier for Stargardt's disease, possessing only the paternal mutant allele.
The authors of the case report, Ms. Masha Sohrab and Professor R. Theodore Smith, stated that this new application of pre-implantation genetic diagnosis in Stargardt's disease represented the first reported case for an autosomal recessive retinal dystrophic disease. While significant research and genetic aetiology for Stargardt's disease has been reported in recent years, treatment options have remained limited. Prognosis at present indicates that patients with the disease experience a progressive bilateral decline in their vision between the ages of 6 and 20 years leading to a visual acuity of 20/200 with associated central scotoma. As such, pre-implantation genetic diagnosis may provide a viable alternative for at risk or affected couples who wish to avoid passing the disease to their offspring. The case report was published in the April 2010 issue of American Journal of Ophthalmology, Vol. 149, No. 4, pp 651-655.
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