The craniofacial complex in 47,XYY males

Crown heights in the permanent teeth of 47,XYY males

OBJECTIVE

The results in human sex chromosome aneuploidies had shown that the extra Y chromosome increases permanent and deciduous tooth crown sizes in the mesiodistal and labiolingual directions. The hypothesis of the study was that the additional Y chromosome increases the permanent tooth crown growth in a vertical dimension. We also aimed to observe possible sex difference in the permanent tooth crown height.

MATERIAL AND METHODS

Data on 15 47,XYY males or males with an extra Y chromosome, nine male relatives (five brothers and four fathers) and 45 male and 48 female population controls had been gathered previously for Professor Lassi Alvesalo's KVANTTI Research Project. The measurements from panoramic radiographs were performed of all the applicable teeth, except the third molars on both sides of the jaws with a sliding digital calliper.

RESULTS

All the mean tooth crown heights in the 47,XYY males were larger than in the male population controls and the differences were statistically significant in six teeth in the maxilla and 10 teeth in the mandible. Apart from few teeth, the crown heights in the 47,XYY males were larger than in their male relatives, but the difference between these groups was significant only in one tooth. The differences between sexes were statistically significant in eight teeth in the maxilla.

CONCLUSIONS

Based on previous investigations and this work, it is evident that the impact of the extra Y chromosome during tooth crown development is holistic, increasing permanent tooth sizes in three dimensions in a balanced manner.

Root Lengths in 47,XYY Males’ Permanent Teeth

Studies on individuals with sex chromosome anomalies have demonstrated the promoting effect of the Y chromosome on tooth crown enamel and dentin growth. The present research investigated permanent tooth root lengths in 47,XYY males. The measurements were made from panoramic radiographs. The results indicate longer tooth roots in 47,XYY males compared with those in control males and females. The promoting effect of the Y chromosome on dental growth thus continues in the form of root dentin after the completion of crown growth. The results, together with those on tooth crown sizes in 47,XYY males, suggest that growth excesses are evident and final, beginning a few months after birth and continuing up to the age of 14 years, at least. The excess root dentin growth in 47,XYY males, as well as sexual dimorphism in the growth of crown and root dentin, might be caused by the same factor on the Y chromosome.

XYY Karyotype in a Mentally Retarded Man with Prognathism and Malformation of His Hands and Toe Nails

We report on a 25-year-old man who was referred for evaluation of possible Fragile X syndrome on the basis of mild mental retardation and malformation of his hands and toe nails. He was found not to have this syndrome but to have a 47, XYY karyotype. Only one other case of XYY syndrome with prognathism and malformation of hands has been reported.

47 XYY and morning glory syndrome--a unique association

47 XYY syndrome is a sporadic condition in which the human male receives an extra Y chromosome. Few ocular associations have been documented. The authors report the first case of 47 XYY associated with morning glory syndrome, frontonasal meningoencephalocele, and midfacial defects.

The craniofacial complex in 45,X/46,XX females

Fourteen Finnish 45,X/46,XX females were compared with population female and male controls, and in addition, nine of them were compared with their first-degree female relatives. Linear and angular measurements were made from standardized lateral cephalograms of patients and normal population controls from the "Kvantti" study series. In both comparisons the results indicated that craniofacial dimensions in 45,X/46,XX females were smaller than those in population female and male controls. The general metric pattern was similar to that observed in relation to the tooth crowns of 45,X/46,XX females. Several of their craniofacial proportions and plane angles differed from those of normal women: shorter anterior and posterior cranial bases and a flatter cranial-base angle, a sagittally shorter maxilla and a sagittally shorter mandible with an enlarged ramus:corpus length ratio, posterior rotation of the mandible and a tendency to bimaxillary retrusion. It is suggested that the reduction of X-chromosomal genetic material in 45,X/46,XX females results in smaller craniofacial dimensions than in normal females, with substantial effects on dimensional ratios and especially plane angles of the cranial base.