Anthropometric and craniofacial patterns in mentally retarded males with emphasis on the fragile X syndrome

Abstract

Anthropometric and craniofacial profile patterns indicating the percent difference from the overall mean were developed on 34 physical parameters with 31 white, mentally retarded males (23 adults and 8 children) with the fra(X) syndrome matched for age with 31 white, mentally retarded males without a known cause of their retardation. The fra(X) syndrome males consistently showed larger dimensions for all anthropometric variables, with significant differences for height, sitting height, arm span, hand length, middle finger length, hand breadth, foot length, foot breadth, and testicular volume. A craniofacial pattern did emerge between the two groups of mentally retarded males, but with overlap of several variables. Significant differences were noted for head circumference, head breadth, lower face height, bizygomatic diameter, inner canthal distance, ear length and ear width, with the fra(X) syndrome males having larger head dimensions (head circumference, head breadth, head length, face height and lower face height), but smaller measurements for minimal frontal diameter, bizygomatic diameter, bigonial diameter, and inner canthal distance. Several significant correlations were found with the variables for both mentally retarded males with and without the fra(X) syndrome. In a combined anthropometric and craniofacial profile of 19 variables comparing 26 white fra(X) syndrome males (13 with high expression (>30%) and 13 with low expression (< 30%), but matched for age), a relatively flat profile was observed with no significant differences for any of the variables. Generally, fra(X) syndrome males with increased fragile X chromosome expression have larger amplifications of the CGG trinucleotide repeat of the FMR-1 gene. No physical differences were detectable in our study between fra(X) males with high expression and apparently larger amplifications of the CGG trinucleotide repeats compared with those patients with low expression. Our research illustrates the use of anthropometry in identifying differences between mentally retarded males with or without the fra(X) syndrome and offers a comprehensive approach for screening males for the fra(X) syndrome and selecting those individuals for cytogenetic and/or molecular genetic testing. 1983, Meaney & Farrer 1986, Meaney & Butler 1989, Butler et al. 1991a. One of these conditions is the fragile X (fra(X)) or Martin-Bell syndrome, the most common familial cause of mental retardation. This syndrome is characterized by mental retardation, macroorchidism, large or prominent ears, a long narrow face, hyperflexibility and a characteristic chromosome fragile site at Xq27.3 (Turner et al. 1986, Hagerman 1987, Butler 1988. The incidence of the fragile X syndrome is approximately one in 1000-2500 males (Herbst & Miller 1980, Turner et al. 1986, Webb et al. 1986). Unstable DNA sequence representing large increases in the number of CGG repeats have recently been located at the fragile site and characterization of the gene (FMR-1) implicated in the fra(X) syndrome is under...

Unstable Mutations in the FMR1 Gene and the Phenotypes

“…28 Large testicles (macroorchidism) begin to occur at about 8 years of age and they reach their maximal size, typically at 2 to 3 times normal (60 ml) at about 15 to 16 years. 59 …”

Anthropometric growth study of auricle of healthy preterm and term newborns

“…Auricular anthropometric studies of various syndromes have been published [6][7][8][9]. Although there have been anthropometric studies of the auricle for normal population from birth to 18 years old [5,10], auricular anthropometric studies in healthy prematures and matures are quite limited and insufficient [11,12].…”

Fragile X syndrome: panoramic radiographic evaluation of dental anomalies, dental mineralization stage, and mandibular angle

“…Our results suggest that the long face observed in the patients with FXS 2,4,7,15 could explain the increase in mandibular angle. Further evaluation of cephalometric studies is necessary to confirm the above mentioned hypothesis.…”

“…Their cephalic perimeter is increased and the bizygomatic diameter and internal intercanthal distance are diminished. In addition, their height, wingspan, and length of hands, feet, and digits are also significantly increased 2 .…”