posted 12/02/02
Researchers describe a "familial clustering"
in retinopathy secondary to type 2 diabetes mellitus. They observed a more than
three-fold higher prevalence of retinopathy among siblings of patients with
diabetic retinopathy.
The occurrence of diabetic retinopathy in some
patients with good glycemic control "points to the possible role of genetic
factors in conferring susceptibility to retinopathy," Dr. M. Rema and colleagues
from the Madras Diabetes Research Foundation report.
To investigate a possible genetic basis for
retinopathy in type 2 diabetes mellitus, Dr Rema's team evaluated 322 families
having at least two siblings. In each family, the sibling with longest standing
diabetes was identified as the proband. A detailed clinical, biochemical and
retinoscopic examination estimated the prevalence of retinopathy in the probands
and in 355 other siblings with type 2 diabetes.
Diabetic retinopathy was present in 136 probands
and in 53 (35.3%) of their siblings, Dr. Rema and colleagues report in the
November issue of Diabetic Medicine. In contrast, the prevalence of retinopathy
among siblings of probands without retinopathy was only 11.2%, they note.
Siblings of patients with diabetic retinopathy
had a 3.37 higher odds ratio of developing retinopathy compared with siblings of
diabetics without retinopathy, the researchers report. The higher risk of
retinopathy was not influenced by duration of diabetes, glycemic control, or the
presence of hypertension, they add.
The "familial clustering of retinopathy" could
have a genetic or environmental basis, Dr Rema and colleagues write. A previous
report of familial clustering of microalbuminuria "suggests a similar pattern of
inheritance of microangiopathy among diabetic subjects," the investigators
postulate.
The genetic basis for retinopathy in type 2
diabetes can be explained by the presence of strong "familial aggregation," even
after correcting for glycemic status and duration of diabetes, Said, Dr Rema.
"There seems to be a separate genetic basis to diabetic retinopathy apart from type 2 diabetes," Dr Rema concludes.
Source: Diabetes In Control Dot Com: Diabet Med
2002;19:910-916.
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