Archs oral Bid. Vol. 42, No. 8, pp. 579-586, 1997 0 1997 Elsevier Science Ltd. All rights reserved

PII: SOOO3-9969(97)00047-Z Printed in Great Britain

0003-9969197 $17.00 + 0.00

THE CRANIOFACIAL COMPLEX IN 47,XYY MALES

MATHIAS GRON,’ KATI PIETILA’ and LASS1 ALVESALO’

‘Department of Oral Development and Orthodontics, Institute of Dentistry, University of Oulu, Finland

(Accepted 15 April 1997)

Summary--Eight adult, Finnish 47,XYY males were compared with population male and female con- trols and, in addition, three of them were compared with first-degree male relatives. Linear and angular measurements were made from standardized lateral cephalograms of patients and normal population controls from the “Kvantti” studv series. In both comuarisons the craniofacial dimensions in 47.XYY males were larger than those in population male and female controls. Their craniofacial proportions and plane angles were similar to those of normal men except for a larger lower facial height with pos- terior rotation of the mandible and a tendency to bimaxillary protrusion, a longer cranial base and a lesser cranial-base angle. Thus the supernumerary Y chromosomal gene(s) in 47,XYY males may result in larger craniofacial dimensions than in normal males, without substantial effects on dimensional ratios and plane angles. This general metric pattern is similar to that observed in relation to many adult body and head dimensions, and the dental arches and tooth crowns, of 47,XYY males. The foramen mag- num in 47,XYY males was smaller in the sagittal plane than that of normal males and females. 0 1997 Elsevier Wence Ltd

Key words: 47, XYY males, chromosome aneuploidy, craniofacial complex, Y chromosome.

INTRODUCTION

Effects of the human Y chromosome on skeletal maturation, statural growth and tooth-crown size have been reported by various investigators (Tanner et al., 1959; Ferguson-Smith, 1965; Alvesalo, 1971; Simpson, 1976). The sex-determining region (SRY) is on the short a.rm of the Y chromosome. Among the factors tentatively assigned to the long arm of the Y chromosome is the one preventing azoosper- mia and those affecting stature, tooth size and skel- etal-age retardat:lon. (Alvesalo and de la Chapelle, 1981; Biihler, 1950; Vergnaud et al., 1986; Bardoni et al., 1991; Therman and Susman, 1993; Salo et al., 1995a). The size and shape of the craniofacial complex are alrected in individuals with sex- chromosome anomalies. In general, an additional Y chromosome increases linear dimensions, and extra sex chromosomes seem to be associated with a more acute angle of the cranial base (Rzymski and Kosowicz, 1975. 1976; Peltomgki et al., 1989; BarbiC et al., 1991; Brown et al., 1993). Mild facial dysmorphism with a small chin and mouth and a highly arched or cleft palate in males with the del- etion of Yq war, recently reported by Salo et al. (1995b).

It is estimated that one 47,XYY male is born for every 700 males. Individuals range from fully fertile to sterile (Therman and Susman, 1993). Levels of

Abbreviations: cephalometric abbreviations are explained in figures and text.

plasma testosterone are similar to those in normal males (Simpson, 1976). Results of a longitudinal study of statural growth indicate that the additional Y chromosome in 47,XYY males causes a doubling of the magnitude of sexual dimorphism of growth in man, and that completion of growth in 47,XYY males occurs on average 6 months later than in nor- mal male controls (Ratcliffe et al., 1992).

Body and head dimensions in 47,XYY males are greater than averages for both control males and male relatives. Body proportions are similar to those in normal men (Varrela and Alvesalo, 1985; Stewart et a/., 1982; Ratcliffe et al., 1990). This sup- ports the concept that Y-chromosomal gene(s) (Ogata and Matsuo, 1993; Smith et al., 1985) affect somatic characteristics other than stature. In a longitudinal study of IQ, social status, stature and head circumference in children from birth to 14 years of age, 47,XYY males were found to have lower IQs and head circumference/height ratios than control males, but their head circumferences did not differ from those in normal males, although there was a brief increase in head-circumference growth velocity between 2 and 3 years of age (Ratcliffe et al., 1994).

In studies of the mouths of 47,XYY males, per- manent and deciduous teeth were found to be larger in both the mesiodistal and labiolingual dimensions, and permanent teeth exhibited less variation than those of normal male population controls and of first-degree male relatives (Alvesalo et al., 1975;

579

580 M. Gron et al

Fig. 1. Reference points and planes used in the cephalometric analysis. Points: S-sella: the midpoint of Sella Turcica; N-nasion: the extreme anterior point on the frontonasal suture; sna-spina nasalis anterior: the extreme anterior point on the maxilla; snp-spina nasalis posterior: the extreme posterior point on the maxilla; Pt-pterygoid point: the extreme superior point of the pterygopalatine fossa; A- point A: the deepest point in the curvature of the maxillary alveolar process; B-point B: the deepest point in the curvature of the mandibular alveolar process; Pg-pogonion: the extreme anterior point of the chin; Me-menton: the extreme inferior point of the chin; Gn-gnathion: the midpoint between pogonion and menton; Go-gonion: the midpoint of the mandibular angle between ramus and corpus mandibulae; 0-opisthion: the posterior border of foramen magnum; Ba-basion: the anterior border of foramen magnum; Cd-condylion: the extreme superior point of the condyle; Fc-fossa cranialis: the intersection between the sphenoidal plane and the larger wing of the sphenoid; L-lambda: the mid- point of the lambdoid suture on the external cranial contour. Planes: s-n-the sella-nasion line; sph- the sphenoidal plane; cliv-the clival plane; for-the foramen magnum plane; pal-the palatal plane (sna-snp); occ-the occlusal plane (see Fig. 2: from the intersection of the upper and lower incisors to the occlusal contact of the upper and lower first molars): man-the mandibular plane (a tangent to the lower border of the mandible); ram-the ramal plane (a tangent to the dorsal surface of the ramus

with exclusion of the condyle); N-A-the nasion-A line; N-B-the nasion-B line.

Alvesalo and Kari, 1977; Townsend and Alvelsalo, 1985). 47,XYY males tended to exhibit mesial molar occlusion, mandibular overjet and incisal open bite more often than male population controls (Laine et al., 1992) and a wider palate and longer maxillary and mandibular alveolar arches (Laine and Alvesalo, 1993).

Our aim now was to analyse the influence of the Y chromosome on the size and shape of the cranio- facial complex in 47,XYY males.

PARTICIPANTS AND METHODS

Eight Finnish 47,XYY males aged 15.8-36.7 years at the time of examination (mean 21.7 years) were studied. The 47,XYY males had been karyo- typed because of various behavioural problems (e.g. mental subnormality, aggressiveness, criminality,

etc.) The controls were three first-degree male rela- tives aged 19.1-31.8 years (mean 23.5 years), 26 normal males aged 17.9-41.9 years (mean 26.9 years) and 37 normal females aged 16.1-45.4 years (mean 25.4 years), taken from the same “Kvantti” study series of individuals with sex-chromosomal abnormalities and normal control individuals as the 47,XYY males. The participants were radiographed and a cephalometric analysis comprising linear and angular measurements was made from standardized lateral cephalogrdms. Reference points and planes used are shown in Figs 1 and 2. A sliding digital calliper (VIS, MAUa-E, Fabrik fur feinmechanische Erzeugnisse “General Swierczewski”, 01-234, Warsaw, Poland) was used to measure distances between reference points (marked in pencil on a matt acetate film) to the nearest 0.5 mm. Angular measurements were made to the nearest degree,

asp

A zk urn occ

is I

47,XYY craniofacial complex

Fig. 2. Occlusal analysis reference points from which measurements were made parallel to the occlusal plane: is---incision superius: the tip of the crown of the most anterior maxillary central incisor; asp- apex superius: the root apex of the most anterior maxillary central incisor; urn-upper first molar: its most mesial point; ii-incision inferius: the tip of the crown of the most anterior mandibular central incisor; ai-apex inferius: the root apex of the most anterior mandibular central incisor; Im-lower first molar: its most mesial point; occ--the occlusal plane (from the intersection of the upper and lower inci- sors to thz occlusal contact of the upper and lower first molars): A-point A: the deepest point in the curvature of the maxiallary alveolar process; B-point B: the deepest point in the curvature of the man- dibular alveolar process; Pg-pogonion: the extreme anterior point of the chin: Go-gonion: the mid-

point of the mandibular angle between ramus and corpus mandibulae.

using a protractesr. Figures 1 and 2 show the vari- ables used in tbe analysis. When there were two images of a structure, the reference point was placed at the midpoint between the images. No cor- rection was malie for enlargement of the radio- graphs (8.7%).

Intra-observer method error was analysed using a method suggested by Bland and Altman (1986). Lateral cephalograms of 20 patients of the Dental Clinic of the University of Oulu were traced and measured twice. The estimated error between the measurements was calculated using the formula:

SDQ’ = dm

??t2SDrl; the limits within which 95% of the differ- ences between the repeated measurements are expected to lie.

The error of measurement given in &2SD of the differences between the repeated measurements ran- ged between f0.03 and kO.36 (mean limit kO.29) with the greatest error in the S-Cd dimension in the linear measurements and between f0.27 and +0.67 (mean limit f0.37) with the greatest error in the sph/man angle in the angular measurements: thus it was estimated not. to be significant.

The cranioFdcia1 dimensions and plane angles of eight 47,XYY males were compared with those of control males using the Mann-Whitney U-test. In addition, three of them were compared with first- degree male relatives. (Population female means were presented for reference.) All the participants included in the analyses were over 15.8 years of age and had not lost more than six permanent teeth. Four of the 47,XYY males were between 15.8 and 18 years old, while only one of the control males was under 18 (17.9 years). As 47,XYY males are known to complete growth on average sixth months later than normal males, the difference between

fully grown 47,XYY males and control population males could be greater than found in this study.

RESULTS

The results of the comparisons between the eight 47,XYY males and the 26 male population controls, with the mean values for 37 control females for reference, and the ratios relating to the 47,XYY males with mean values greater than those of con- trol males are shown in Table 1. Ratios relating to 47,XYY males with greater values than a first- degree male-relative, as well as mean values and the ratios relating to the three 47,XYY males with greater mean values than their relatives, are shown in Table 2. The 47,XYY males in general exhibited larger dimensions than the population control males and females. Dimensional ratios and plane angles resembled those in normal men.

The 47,XYY males had significantly longer an- terior (S-N,Fc-N) and posterior (Ba-Pt) cranial bases than control males, but the foramen magnum (0-Ba) was sagittally smaller than in control males. The maxilla was positioned significantly more ante- riorly in relation to the cranial base (S-sna. S-snp) in 47,XYY males, and the maxilla (SNA) and man- dibule (SNB) were significantly more prognathic than in control males. These features were ac- companied by a reduction in cranial-base angle. The 47,XYY males had significantly longer mand- ibles (Cd-Gn), with emphasis on the mandibular corpus (Go-Pg), and significantly smaller ramus to corpus length ratios (Cd-Go/Go-Pg) than control males. The mandibular corpus also tended to be longer in proportion to the anterior cranial base (Go-Pg/S-N) than in normal men.

The lower facial height (sna-Me) was significantly greater in 47,XYY males than in control males. This finding was supported by statistically non-sig-

582 M. Griin et al.

Table 1. Cephalometric dimensions (in mm), dimensional ratios and angles of 47,XYY men and controls of both sexes

Mann- Whitney U-

Wilcoxonrank sum W-test

(47,XYY males vs

47,XYY males (n = 8) Control males (n = 26) Control females (n = 37) control males)

Mean (SD) Mean (SD) Mean (SD) 2-tailed p

value

Age (yrs) LINEAR DIMENSIONS Cranial base S-N S-Fc Fc-N S-Ba Ba-Pt Fc-Pt S-L 0-Ba

Cranial base to maxillary complex S-Cd O-Cd O-Go S-Go N-Me N-sna S-Sna S-Snp

Maxillary complex sna-Me sna-snp A-snp Go-Pg Cd-Go Cd-Gn

Dental complex is-urn asp-urn A-urn ii-lm ai-lm B-lm sna-urn snp-urn Pg-lm Go-lm

21.65 8.12 26.88 6.3 25.43 8.58

79.44 3.94 76.38 3.42 72.91 3.28 29.69 2.7 29.15 2.78 27.43 2.7 53.06 10.86 47.15 3.7 45.3 1 3.15 51.06 3.16 48.35 3.33 45.91 2.72 57.13 3.31 52.62 4.34 52.16 3.13 22.06 3.01 20.08 3.2 18.01 2.82

118.94 2.9 118.65 5.77 115.32 5.27 31.69 3.33 36.46 3.14 33.16 2.93

27.81 3.84 25.25 3.03 23.09 3.12 52.06 4.19 54.25 3.17 51.46 3.82 69.94 5.47 67.58 7.9 61.47 5.37 88.19 4.33 82.88 17.2 76.74 5.89

134.0 7.68 130.81 6.79 120.77 6.15 56.63 4.14 57.56 3.51 53.55 2.67 99.81 5.71 94.12 4.56 89.03 4.61 57.44 4.60 53.56 3.4 49.99 2.98

78.81 5.61 74.65 5.08 68.95 5.03 59.31 3.48 56.38 3.56 53.74 2.83 54.38 3.81 51.77 3.44 48.88 2.69 88.13 7.48 82.3 1 5.18 78.77 5.67 62.88 2.79 64.79 5.75 56.53 4.42

132.44 5.72 127.62 6.64 117.45 6.98

30.06 3.51 28.75 2.65 28.55 2.89 16.69 4.03 18.08 3.14 17.31 2.86 21.69 3.43 21.67 3.26 20.70 3.26 26.13 5.4 23.77 3.89 24.8 2.5 16.69 4.23 15.06 4.45 14.65 3.89 22.94 4.13 20.35 4.21 20.14 3.85 25.88 3.59 26.40 3.91 25.22 3.55 32.44 3.09 30.65 5.82 27.86 3.05 26.75 4.62 24.15 5.26 23.27 4.71 59.19 7.92 55.90 5.66 53.28 6.1

0.0360* 0.7756 0.0250* 0.0795 0.0267* 0.3809 1.000 0.0028* 47,XYY > control

males ratio: 718

0.0643 0.1435 0.5556 0.2812 0.2007 0.7915 0.0105* 0.0419* 47,XYY > control

males ratio: 618

0.0462* 0.0609 0.1668 0.0184* 0.4278 0.0297* 47,XYY > control

males ratio: 516

0.3805 0.4042 0.9351 0.2075 0.3093 0.0669 0.8549 0.0672 0.1861 0.2907 47,XYY > control

males ratio: S/l0

Table I-Continued

DIMENSIONAL RATIOS

47,XYY craniofacial complex 583

sna-snp/Go-Pg 0.68 ma-snp/S-N 0.75 Go-Pg/S-N 1.11 S-Go/N-Me 0.66 N-sna/sna-Me 0.72 asp-urn/is-urn 0.55 ai-lm/ii-lm 0.64 Cd-Go/Go-Pg 0.72

ANGLES Cranial base sph-S-N sph/cliv for/cliv Maxillary complex sagittal SNA SNB ANB

16.75 2.66 14.0 5.47 16.46 5.58 0.1162 106.88 4.45 109.15 6.21 110.86 6.40 0.3701 123.75 7.11 123.92 6.60 126.95 4.90 0.9351

86.88 3.31 82.77 3.97 82.41 4.14 83.88 2.90 79.96 3.74 78.62 3.47

3.00 2.07 2.81 2.97 3.78 2.67

0.08 0.03 0.09

0.69 0.06 0.74 0.04 1.08 0.07 0.64 0.13 0.77 0.06 0.63 0.1 0.63 0.12 0.79 0.08

0.68 0.74 1.08 0.64 0.78 0.61 0.59 0.72

0.05 0.4526 0.04 0.7607 0.08 0.208 1 0.05 0.5976 0.07 0.0563 0.09 0.1938 0.12 0.5697 0.06 0.0384*

0.0144* 0.0108* 0.9837 47,XYY > control

males ratio: 313

0.0938 0.1928 0.5400 0.5687 0.9189 0.4514 0.9838

0.04 0.07 0.1 0.08 0.07

Maxillary complex vertical pal/occ pal/man manjocc man/ram man/s-n sph/man for/man

8.63 26.50 17.75

119.75 30.25 13.5 30.38

4.10 5.88 7.58 22.85 4.71 16.77 8.33 117.31 6.16 30.23

3.28 5.23 3.95 6.58 6.34 8.58 8.54

8.22 3.57 24.43 4.87 16.03

116.84 31.51 14.89 30.51

4.14 7.44 5.8 5.91 6.1

6.35 15.96 8.9 30.85

*Comparisons between 47,XYY and control males significant at the 0.05 level.

nificant findings of a greater gonial angle (man/ ram), a greater angle between the maxillary and mandibular plants (pal/man), and of a reduced upper to lower anterior facial height ratio (N-sna/ sna-Me) compared with population control males (Table 1).

The comparison of the three 47,XYY males with three first-degree male relatives revealed similar trends for the cranial base, distances from the cra- nial base to the maxillary complex, maxillary com- plex, dental complex and dimensional ratios (Table 2) to those from the comparison of all the 47,XYY males wit.h the male controls.

of a double dose of Y chromosomal genes affecting proliferative and appositional growth in the cranio- facial complex. The effects on mandibular dimen- sions may be a result of increased proliferative growth in the condyle. In sutures and synchon- droses of the cranial base and the maxilla the effect may be a result of increased intramembranous apposition. This increased growth, accompanied by a more acute cranial-base angle, might be followed by alteration of the mandibular growth pattern, leading to slight posterior rotation of the mandible.

Generally, 47,XYY males exhibit larger craniofa- cial dimensions than population control males and females. Apart from the increase in lower facial height, with posterior rotation of the mandible, and a tendancy to bimaxillary protrusion with a longer mandible, a smaller ramus-to-corpus length ratio, a longer cranial base and a decreased cranial-base angle, dimensional ratios and plane angles in 47,XYY men resemble those of normal men. The results indicate that the anterior cranial base in 47,XYY males is longer, and the cranial-base angle more acute than in normal male controls. The find- ing of larger size is in agreement with findings by Varrela and Alvesalo (1985) of larger body and head dimensions in 47,XYY men than in normal men, but normal body proportions. An association between a reduction in cranial-base angle and

DISCUSSION

To the best of our knowledge this is the first pub- lished report on the dimensions and form of the craniofacial complex in 47,XYY males. Data from tooth-crown stud& show that the Y chromosome influences growth of both dentine and enamel, probably because of the proliferative activity of odontoblasts and the secretory activity of amelo- blasts (Alvesalo and Tammisalo, 1981; Alvesalo, 1985; Alvesalo et al., 1985, 1987, 1991). Assuming pleiotropy (i.e. possession by a gene of more than one phenotypic effect), the larger craniofacial dimensions in 47,XYY males may be a consequence

584 M. Griin et al.

supernumeracy sex chromosomes and an increase in that the mandibles were longer in the males with an this angle with loss of sex chromosomes was extra Y chromosome studied than in normal males reported by Rzymski and Kosowicz (1976) in is parallel to the findings of Pietila et al. (1997) that 47,XYY men and 47,XxX women, and by the mandibular corpus was longer in 46,XY females Peltomaki et aZ. (1989) in 45,X females. Our finding with androgen insensitivity than in normal women,

Table 2. Cephalometric dimensions (in mm), dimensional ratios and angles of three 47,XYY men and three of their male first- degree relatives

47,XYY males (n = 3) Male relatives (n = 3)

47,XYY male individual > Mean (SD) Mean (SD) his male relative (ratio)

Age (yrs) LINEAR DIMENSIONS Cranial base S-N S-Fc Fc-N S-Ba Ba-Pt Fc-Pt S-L 0-Ba

Cranial base to maxillary complex S-Cd O-Cd O-Go S-Go N-Me N-sna S-sna S-snp

Maxillary complex sna-Me sna-snp A-snp Go-Pg Cd-Go Cd-Gn

Dental complex is-urn asp-urn A-urn ii-lm ai-lm B-lm sna-urn snp-urn Pg-lm Go-lm

DIMENSIONAL RATIOS sna-snp/Go-Pg sna-snp/S-N Go-Pg/S-N S-Go/N-Me N-snaisna-Me asp-urn/is-urn ai-lmiii-lm Cd-do/Go-Pg

23.63 11.32 23.5 7.22

77.67 1.04 78.0 1.5 28.67 2.08 28.5 2.6 58.33 17.47 49.17 2.75 52.83 2.84 48.0 2.5 57.83 2.89 53.83 1.89 22.0 3.5 21.0 3.97

118.5 3.12 119.33 3.51 30.5 3.77 33.5 6.0

30.17 2.57 26.67 2.08 48.83 0.76 51.17 6.0 69.17 5.69 70.5 4.58 90.0 3.61 89.33 0.29

135.67 9.36 126.5 7.86 59.17 1.04 56.17 1.89 97.83 2.75 92.17 1.26 56.5 2.78 50.33 5.3

77.33 7.75 70.5 8.66 58.5 2.6 55.0 2.5 54.33 3.21 50.17 2.47 88.67 3.82 83.5 4.0 63.33 2.02 65.67 2.31

132.0 6.93 123.33 3.69

28.33 1.61 28.67 3.62 15.17 3.06 16.5 1.32 21.33 2.93 21.67 1.89 23.33 3.88 23.67 1.04 15.33 2.52 14.5 1.8 21.17 3.21 21.33 1.26 25.17 3.21 26.67 2.84 32.67 3.62 28.33 2.08 25.83 4.01 25.67 3.55 61.33 4.48 57.17 2.84

0.66 0.06 0.66 0.03 0.75 0.04 0.71 0.04 1.14 0.04 1.07 0.07 0.67 0.07 0.71 0.04 0.77 0.07 0.8 1 0.13 0.53 0.09 0.58 0.05 0.66 0.04 0.62 0.11 0.72 0.05 0.79 0.05

O/3 t/3 213 313 313 313 213 213

47,XYY > male relatives ratio: 518

213 f/3 l/3 l/3 313 313 313 313

47,XYY > male relatives ratio: 618

313 3/3 313 213 O/3 313

47,XYY > male relatives ratio: 516

l/3 l/3 l/3 213 t/3 l/3 l/3 213 l/3 213

47,XYY > male relatives ratio: 4110

t/3 313 213 O/3 t/3 l/3 213 O/3

47,XYY craniofacial complex 585

Table 2-Contintied

ANGLES Cranial base sph/S-N 16.67 sph/cliv 106.67 for/cliv 118.0 Maxillary complex sag&al SNA 84.67 SNB 82.33 ANB 2.33

Maxillary complex vertical pal/occ 7.67 pal/man 23.67 man/occ 15.67 man/ram 118.0 man/s-n 29.0 sph/man 12.33 for/man 23.67

Abbreviations as in Table 1

2.52 5.13 4.36

4.73 3.51 1.53

3.21 7.77 4.16 5.57 7.81 8.62 7.64

15.33 111.33 124.0

82.0 79.0

3.0

4.0 14.67 10.67

107.0 24.0

9.0 22.0

5.86 10.02 4.36

0 5.0 5.0

3.61 9.61 6.03 8.19 7.0 8.72 4.58

213 l/3 J/3

213 213 213

47,XYY > male relatives ratio: 2/3

313 313 313 313 313 213 t/3

Table 3. DimensIonal ratios calculated from the studies by Peltomaki et al. (1989) and Brown et al. (1993) on 45,X females and 47,XXY males for comparison with our 47,XYY males and 46,XY male controls

45,X females 47,XXY males 46,XY males 47,XYY males

(Peltomlki et al. (1989)) (Brown et al. (1993)) (present study) (present study) Mean ir = 64 Mean n = 26 Mean n = 26 Mean n=8

DIMENSIONAL RATIOS sna-snp/Go-Pg 0.72 0.66* 0.69 0.68 sna-sup/S-N 0.74 0.7 0.74 0.75 Go-Pg/S-N 1.02 1.05* 1.08 1.11 S-Go/N-Me 0.62 0.69* 0.64 0.66 N-sna/sna-Me 0.77 0.75 0.77 0.72 Cd-Go/Go-Pg 0.75 0.75* 0.79 0.72

*Brown ef al. (1993) used the tGO-point when measuring the length of the mandibular corpus

and with the findings of Grijn and Alvesalo (1997) that such women had more mesial occlusion than normal women. .4lthough it is not clear to us what caused the foramen magnum to be smaller in the sagittal plane in 47,XYY males than in normal males, a finding we did not expect, we suggest that it could have been a result of the observed longer clivus, also possibly of a general increase in growth in the posterior margin of the occipital bone. On comparing dimensional ratios calculated from results of studies by Peltomaki et al. (1989) of 45,X females and Brown et al. (1993) of 47,XXY males, with results relating to the 47,XYY males and population control males in our study (Table 3) effects of reduced or additional sex-chromosome material are evident. The mandibular corpus tends to gain length in proportion to the anterior cranial base (Go-Pg/S-N) with addition of sex chromo- somes. The upper-to-lower anterior face height ratio (N-sna/sna-Me) seems to be reduced by an

extra Y chromosome, and to some extent by ad- dition of an X chromosome.

We suggest that the supernumerary Y chromoso- ma1 gene(s) in 47,XYY males results in larger cra- niofacial dimensions than in normal males, without substantial effects on dimensional ratios and plane angles. This general metric pattern is similar to that observed in relation to many adult body and head dimensions and dental arches and tooth-crowns of 47,XYY males. the foramen magnum in 47,XYY males was found to be smaller in the sagittal plane than the foramen magnum in normal males and females.

Acknowledgements-We thank Associate Professor Juha Tienari and Jouko Remes, M.Sc., of the Department of Applied mathematics and Statistics of the University of Oulu for statistical analysis of the data. The study was supported by the Academy of Finland and the University of Turku Foundation.

586 M. Gr %n el al.

REFERENCES

Alvesalo L. (1971) The influence of sex-chromosome genes on tooth size in man. Proc. Finn. Dent. Sot. 67, 3-54.

Alvesalo L. (1985) Dental growth in 47,XYY males and in conditions with other sex-chromosome abnormalities. In The Y-chromosome, Part B: Clinical Aspects of Y Chromosome Abnormalities (Ed. Sandberg A. A.), pp. 277-300. Alan R. Liss, New York.

Alvesalo L. and Chapelle de la A. (1981) Tooth sizes in two males with deletions of the long arm of the Y- chromosome. Ann. Hum. Gene?. 45, 49-45.

Alvesalo L. and Kari M. (1977) Sizes of deciduous teeth in 47,XYY males. Am. J. Hum. Genet. 29, 486-489.

Alvesalo L., Osborne R. H. and Kari M. (1975) The 47,XYY male, Y chromosome, and tooth size. Am. J. Hum. Genet. 27, 53-61.

Alvesalo L. and Tammisalo E. (1981) Enamel thickness in 45,X females’ permanent teeth. Am. J. Hum. Genet. 33, 464469

Alvesalo L., Tammisalo E. and Hakola P. (1985) Enamel thickness in 47,XYY males’ permanent teeth. Ann. Hum. Biol. 12, 421-427.

Alvesalo L., Tammasalo E. and Therman E. (1987) 47,XYY females, sex chromosomes, and tooth crown structure. Hum. Genet. 77, 345-348.

Alvesalo L., Tammisalo E. and Townsend G. (1991) Upper central incisor and canine tooth crown size in 47,XYY males. J. Dent. Res. 70, 105771060.

Babic M., Mimic M., Jaksic N. and Mi& S. (1991) An extra X chromosome effect on craniofacial morphogen- esis in men. Eur. J. Orrhod. 13, 329-332.

Bardoni B.. Zuffardi 0.. Guioli S.. Ballabio A.. Simi P.. Cavalli P., Grimoldi M. G., Fraccaro M. and Camerino G. (1991) A deletion map of the human Ypll region: implications for the evolution of the Y chromosome and tentative mapping of a locus involved in spermatogen- esis. Genomics 11, 443-45 1.

Bland J. M. and Altman D. G. (1986) Statistical methods for assessing agreement between two methods of clinical measurement. The Lancer 1, 307-310.

Brown T., Alvesalo L. and Towsend G. C. (1993) Craniofacial patterning in Khnefelter (47,XYY) adults. Eur. J. Orthod. 15, 185-194.

Biihler E. M. (1980) A synopsis of the human Y chromo- some. Hum. Cenet. 55, 145-175.

Ferguson-Smith M. A. (1965) Karotype-phenotype corre- lations in gonadal dysgenesis and their bearing on the pathogenesis of malformations. J. Med. Genet. 2, 142- 155.

GrBn M. and Alvesalo L. (1997) Dental occlusion an arch size and shape in karyotype 46,XY females. Eur. J. Orthod. 19, 329-335.

Laine T. and Alvesalo L. (1993) Palatal and mandibular arch morphology in 47,XYY men and in other sex- chromosome anomolies. Archs. Oral &al. 38, 101-105.

Laine T., Alvesalo L. and Lammi S. (1992) A study in 47,XYY men of the expression of sex-chromosome anomolies in dental occlusion. Arch. Oral Biol. 37, 923- 928.

Ogata T. and Matsuo N. (1993) Sex chromosome aberra- tions and stature: deduction of the principal factors involved in the determination of adult height. Hum. Genet. 91, 551-562.

Peltomaki T., Alvesalo L. and Isotupa K. (1989) shape of the craniofacial complex in 45,X females: Cephalometric study. J. Craniof Genet. Dev. Biol. 9, 331-338.

Pietila K., Griin M. and Alvesalo L. (1997) The cranio- facial complex in karyotype 46,XY females. Eur. J. Orthod. (in press), 1996.

Ratcliffe S. G., Butler G. E. and Jones M. (1990) Edinburgh study of growth and development of children with sex chromosome abnormalities. IV. Birth Defects: Original Article Series 26, l-44.

Ratcliffe S. G., Pan H. and McKie M. (1992) Growth during puberty in the XYY boy. Ann. Hum. Biol. 19, 5799587.

Ratcliffe S. G., Masera N., Pan H. and McKie M. (1994) Head circumference and IQ of children with sex chromosome abnormalities. Dev. Med. Child. Neurol. 36, 533-544.

Rzymski K. and Kosowicz J. (1975) The skull in gonadal dysgenesis-a roentgenometric study. C/in. Radiol. 26, 379-384.

Rzymski K. and Kosowicz J. (1976) Abnormal basal angle of the skull in sex chromosome aberrations. Acta. Radiol. Diagn. 17, 669-675.

Salo P., KBBridinen H., Page D. C. and Chapelle de la A. (1995a) Deletion mapping of stature determinants on the long arm of the Y chromosome. Hum. Genet. 95, 283-286.

Salo P., Ignatius J., Simola K. 0. J., Tahvanainen E. and Kdlriainen H. (1995b) Clinical features of nine males with molecularly defined deletions of the Y chromosome long arm. J. Med. Gene?. 32, 711-715.

Simpson J. L. (1976) Disorders of sexual Differentiation. In Disorders of sexual Differentiation, Chap. 12, pp. 361-370. Academic Press, London.

Smith D. W., Marokus R. and Graham J. M. (1985) Tentative evidence of Y-linked statural gene(s)- Growth in the testicular feminization syndrome. C&r. Ped. 24, 189-192.

Stewart D. A., Netley C. T. and Park E. (1982) Summary of clinical findings of children with 47,XXY, 47,XYY and 47,XxX karyotypes. Birfh Defects: Original Article Series 18, l-5.

Tanner J. M., Prader A., Habich H. and Ferguson-Smith M. A. (1959) Genes on the Y chromosome influencing rate of maturation in man. Skeletal age studies in chil- dren with Klinefelter’s (XXY) and Turner’s (X0) syn- dromes. The Lancet 2, 141-144.

Therman E. and Susman M. (1993) Human Chromosomes, Chap. 19, pp. 190-202, Chap. 20, pp. 2033209, Chap. 22. pp. 220-227. Springer, New York.

Townsend G. and Alvesalo L. (1985) Tooth size in 47,XYY males: evidence for a direct effect of the Y chromosome on growth. Austr. Dent. J. 30, 2866272.

Varrela J. and Alvesalo L. (1985) Effects of the Y chromo- some on quantitative growth: an anthropometric study of 47,XYY males. Am. J. Phys. Anthrop. 68, 239-245.

Vergnaud G., Page D. C., Simmler M-C., Brown L., Rouyer, Noel B., Botstein D., Chapelle de la A. and Weissenbach J. (1986) A deletion map of the human Y chromosome based on DNA hybridization. Am. J. Hum. Genet. 38, 109-124.