Application of Gelatin-Coated Magnetic Particles for Isolation of Genomic DNA from Bones.

OBJECTIVE: To develop a method for human genomic DNA extraction from bone using gelatin-coated magnetic particles. MATERIAL AND METHOD: Thirty human metacarpal with the bone age ranging from 36 to 93 years were included in the present study. Genomic DNA was extracted from bones using gelatin-coated magnetic particles. The concentration and purity of DNA were analyzed in comparison with a reference method. In addition, the quality of extracted DNA was examined for sex determination by conventional polymerase chain reaction (PCR). RESULTS: The average DNA concentration using gelatin coated magnetic particles exhibited approximately 15 times higher than a reference method with an insignificantly difference of the DNA purity in both methods. Twelve (40%) and fifteen (50%) samples out of thirty DNA isolated using established and reference method, respectively, could be amplified and sex correctly determined by PCR. CONCLUSION: Gelatin coated magnetic particle is rapid, simple, and well-suited for isolation of DNA from bones.

Determination of sex from the proximal hand phalanges in a Thai population.

A sample of 249 skeletons (154 males, 95 females) from the Chiang Mai University Skeletal Collection was studied to investigate the potential of proximal hand phalanges as indicators of sex among individuals from the Chiang Mai province of Thailand. The sample ranged in age from 19 to 93 years. Six measurements were taken on each proximal phalanx: maximum length, medio-lateral base width, antero-posterior base height, medio-lateral head width, antero-posterior head height and maximum mid-shaft diameter. The measurements were then subjected to ROC analysis as well as binary logistic regression to assess the relative correct allocation accuracy for each bone, and for different combinations of measurements from each bone. All proximal phalanges from both sides exhibited greater than 87% correct allocation accuracy for at least one logistic regression equation that included only two or three measurements. When the sample was limited to individuals with no missing measurements (n=209) in any of the phalanges, the most accurate equations for each proximal phalanx ranged from 87.6% to 92.3%, with the most accurate equation based on two measurements from the left 1st proximal phalanx, and the next most accurate from three measurements of the left 2nd proximal phalanx. The results suggest that proximal phalanges produce better allocation accuracies than metacarpals among modern individuals from Thailand.

Determination of sex from the metacarpals in a Thai population.

Determination of sex using metacarpals was carried out on a sample of 249 skeletons from a Thai population (154 males and 95 females), ranging in age from 19 to 93 years. Six measurements were taken on each metacarpal, namely maximum length, medio-lateral base width, antero-posterior base height, medio-lateral head width, antero-posterior head height and mid-shaft diameter. Binary logistic regression equations were calculated for determining sex from these measurements. All metacarpals from both sides produced at least one equation that correctly allocated the skeletons with 80% or greater accuracy. In a comparative test using only individuals with no missing measurements (n=196), the most accurate equations for each metacarpal on the right side had pooled allocation accuracies ranging from 85.2% to 89.3%, with the best equation based on three measurements from the 5th metacarpal. On the left side, the most accurate equations for each metacarpal ranged from 83.2% to 89.8% correct allocation, with the best equation based on three measurements of the 2nd metacarpal. When the allocation accuracy for each sex is considered in addition to the pooled accuracy, the best equations involve the same three measurements of the 5th metacarpal on the right side, but shift to three measurements of the first metacarpal on the left side, with a pooled accuracy of 88.3%. The results of this study suggest that metacarpals can be used quite reliably for sexing in forensic contexts in Thailand.

Stature estimation from long bone lengths in a Thai population.

The estimation of stature is a very important step in developing a biological profile for forensic identification. However, little previous work has been done on stature estimation among modern Thai people, despite a growing number of forensic cases in Thailand in recent years. The current study was carried out on a sample of 200 skeletons from a northern Thai population (132 males and 68 females), ranging in age from 19 to 94 years. The maximum lengths of six long bones (humerus, radius, ulna, femur, tibia and fibula) were measured and stature reconstruction formulae generated using linear regression. These equations were then tested on a holdout sample of 15 females and 15 males. Results reveal that the three lower limb bones are the most accurate estimators of stature among the males, with the fibula equation producing the lowest standard error of the estimate (SE=4.89cm), followed by the femur (SE=5.06cm). Results for females were mixed. The femur produced the lowest standard error among the females (SE=5.21cm), followed by the radius (SE=5.63cm). However, when tested against the holdout sample (n=30), the femur equations were considerably more accurate, with a mean absolute error of 3.5cm and a median absolute error of 2.4cm. Females exhibited a higher standard error of the estimate than reported in many previous studies. This higher error may be the result of a recent secular trend in stature affecting the females of our sample somewhat more than the males.