Anthropometric comparison of mentally retarded males with and without the fragile X syndrome

Abstract

An anthropometric survey of 41 variables (weight, height, 10 linear, 4 breadth, 22 craniofacial, 2 skinfold, and testicular volume), including multivariate discriminant analysis, was undertaken on 110 mentally retarded males (39 with and 71 without the fra(X) syndrome). The mean Z scores of the fra(X) syndrome males fell between -2.00 and 8.38 for bizygomatic diameter and testicular volume, respectively, and the range of the mean Z scores of the non-fra(X) males was from -2.64 to 2.26 for hand breadth and testicular volume, respectively. There was a statistically significant difference (P less than .05) between fra(X) and non-fra(X) males for 18 measurements (weight, height, 7 linear, 2 breadth, 5 craniofacial, 1 skinfold, and testicular volume), with the greater measurements (excluding bizygomatic diameter) found in fra(X) males. Sitting height, knee-buttock length, middle finger length, and hand length were negatively correlated (P less than .05) with age, whereas bizygomatic diameter, ear length, and ear width were positively correlated (P less than .05) with age and head circumference, head length, and outer canthal distance were positively correlated (P less than .05) with fra(X) chromosome expression in the fra(X) males. Triceps and subscapular skinfold thicknesses were negatively correlated (P less than .05) with age, whereas ankle breadth, ear length, ear width, and nose length were positively correlated (P less than .05) in the non-fra(X) males. Discriminant analysis of 34 fra(X) and 71 non-fra(X) males resulted in a discriminant function based on 6 of 17 anthropometric variables and age.(ABSTRACT TRUNCATED AT 250 WORDS)

Fig. 1

Bar graphs representing average Z score values for all mentally retarded males with and without the fra(X) syndrome.

Fig. 2

Histogram depicting 13 white fra(X) and 50 white non-fra(X) syndrome males classified by discriminant analysis. D = −1.16 + 0.15 (testicular volume Z score) + 0.36 (ear width Z score) − 0.61 (bizygomatic diameter Z score) + 0.47 (head breadth Z score). Also depicted is the test sample of 21 fra(X) syndrome males and 21 non-fra(X) syndrome males who were ungrouped and did not enter into the discriminant equation but received correct classification rates of 95.2% and 90.5%, respectively, according to the discriminant function produced by the variables entered into the discriminant equation from the 13 fra(X) and 50 non-fra(X) syndrome males.

Fig. 3

Histogram depicting 34 white fra(X) and 71 non-fra(X) syndrome males classified by discriminant analysis. D = −1.18 + 0.14 (testicular volume Z score) + 0.35 (ear width Z score) − 0.71 (bizygomatic diameter Z score) + 0.32 (head breadth Z score) + 0.40 (hand breadth Z score) − 0.30 (hand length Z score).