Anthropometric study of length ratio of index finger to the ring (2D:4D) of left hand in healthy and mentally retarded boys 7 to 10 years old of Sistani folk living in Zabol

Finger length ratio can be used in the diagnosis of mentally retardation. The length of fingers is one of the parameters used in anthropometry science which measures linear and angular dimensions of the human body. The present study was conducted to evaluate anthropometric length ratio of index and ring fingers in healthy and mentally retarded to help prevention and early detection of the disease and also provide an archive of numerical data to help hand surgery and manufacturing artificial finger or hand related to the people.
In this study 180 healthy and mentally retarded boys aged between 7 to 10 years old were evaluated in 3 groups of 7-8, 8-9 and 9-10 years old. The distance between fingertips until the last knuckles were measured with a digital caliper. Data were processed by EXCEL 2007, SPSS 16 AND Minitab 16 software. Average data and the second to fourth finger length ratio (2D:4D) in the two groups were compared and related charts were calculated and plotted.
The results showed that the average length of the left hand fingers of the healthy boys was more than ones with mental retardation. So at the same ages in the study it could be said that healthy boys morphologically had fingers longer than mentally retarded ones.
This could be used for prediction and early diagnosis of mental retardation.