ANNALS OF HUMAN BIOLOGY,
1992, VOL. 19, NO. 6, 5 7 9 - 5 8 7
Growth during puberty in the XYY boy S.G. RATCL1FFE~',~H. PAN§and M. MCKIEt tMedical Research Council Human Genetics Units, Edinburgh, UK SDepartment of Growth and Development, Institute of Child Health, London, UK §Department of Mathematics, Statistics and Computing, Institute of Education, London, UK
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Received 30th July 1991; revised 23rd October 1991
Summary. The availability of a cohort of eight unselected XYY boys identified by newborn cytogenetic screening has enabled their growth to be studied longitudinally in comparison with controls from the same population. While no difference had been found in dimensions at birth, increased height velocity in childhood resulted in the XYY boys being 7.6 cm taller at the onset of their pubertal growth spurt. Increased intensity of growth at puberty with a peak height velocity of 10-6cm/year contributed to their adult height of 188.1 cm. XYY boys showed twice the male-female difference in height implying that genes on the Y chromosome exert a quantitative effect on the sexual dimorphism of growth.
1. Introduction Tall stature has been a consistent feature of the descriptions of men with an additional Y chromosome since the first report of an XYY sex chromosome constitution in the human (Sandberg, Koepf, Ishihara and Hauschka 1961) in which the man's height was 183 cm. Following a number o f single case reports, the first major group of XYY men were described in the maximum security hospital in Scotland (Jacobs, Brunton, Melville, Brittain and McClemont 1965); they had a mean height of 185 cm. Most subsequent surveys of mental-penal institutions (Hook 1973) as well as the population based studies (Zeuthen and Nielsen 1973, Noel, Duport, Revil, Dussuyer and Quack 1974, Witkin, Mednick, Schulsinger, Bakkestrom, Christiansen, Goodenongh, Hirschhorn, Lundsteen, Owen, Philip, Rubin and Stocking 1976, Dorus, Dorus, Telfer, Litwin and Richardson 1976) investigated only those males with heights above 183 cm thus introducing a bias in the available records of height of XYY men, and led to an expectation of invariably increased stature. However, review of the literature describing 117 XYY men revealed a height range of 169-223 cm (Ratcliffe 1981). While the evidence implies that generally the second Y chromosome does increase height it would appear that this effect can be negated by adverse environmental factors pre- and post-natally (Faed, Lamont, Morton, Robertson and Smail 1978). As the use of chromosomal analysis in the differential diagnosis of short stature in boys is less frequent than in girls, other short XYY boys may have remained undiagnosed. It has been noted that XYY men are taller than their fathers (Noel et aL 1974) but it is not known whether the parent-offspring correlation is retained in XYY individuals, as it is in conditions such as Klinefelter and Turner syndromes (Brook, Gasser, Werder, Prader, Vanderschueren-Lodewykx 1977). Most of the literature on the growth and body proportions of XYY individuals relates to adults (Milne, Lauder and Price 1974, Alvesalo, Osborne and Kari 1975, Varrela and Alvesalo 1985) as few children with the XYY karotype were identified until the inception of newborn cytogenetic surveys. This resulted in cohorts whose 0301-4460/92 $3.00 © 1992Taylor & Francis Ltd.
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
580
S.G. Ratcliffe et al.
growth could be studied longitudinally, and who were free from selection bias both in height and behaviour. The size of the XYY infant at birth has been shown not to differ from that of chromosomally normal males, both from the collated literature (Chen, Chan and Falek 1971) and from XYY infants identified by cytogenetic screening of consecutive liveborn infants (Ratcliffe 1985). A longitudinal study of a cohort of 14 XYY boys from the above cytogenetic survey has shown height velocity to be significantly increased throughout childhood from age 4 years (Ratcliffe, Butler and Jones 1991). In this report we examine the growth during puberty of eight XYY boys from the survey. We use the optimal kernel (OK) estimation (Gasser, Kohler, Muller, Kneip, Largo, Molinari and Prader 1984) to obtain smoothed distance curves of these individuals and follow this with a new method (VADK)--deriving Velocity and Acceleration from the Distance curve fitted by the Kernel estimation (Pan and Ratcliffe 1991). Characteristic parameters of pubertal growth were then obtained and compared with those of chromosomally normal boys from the same newborn population, studied with the same methods.
2. Subjects and methods 2.1. Subjects Subjects from whom growth measurements have been obtained are: (a) Eight XYY boys identified by cytogenetic screening of consecutive liveborn infants who were at least 18 years of age. Three boys were members of dizygous twin pairs; two pairs of twins were identified in the main survey and the third set in the survey of twin births (Ratcliffe and Paul 1986). (b) The oldest 16 boys from the control group (n = 99 boys) of the Edinburgh Longitudinal Study. These children are known to be chromosomally normal as they were born at a time when the Medical Research Council was conducting the newborn cytogenetic survey. 2.2. Measurements Anthropometric measures were taken by S.G.R. who was trained in measurement techniques by R.H. Whitehouse of the Department of Growth and Development, Institute of Child Health, University of London. The children attended a growth clinic 3-monthly during the first year of life, and twice-yearly thereafter. A range of measures was taken, including height, Using the equipment and techniques identical to those used in the Harpenden study of growth (Tanner 1962). 2.3. Editing Gross errors had been corrected in a previous investigation (Butler, McKie and Ratcliffe 1990). Children were excluded from the analysis if two consecutive measurements were missing after age 6 years.
2.4. Computations Computations were done on a PC/AT compatible computer in Institute of Education, University of London. The program of kernel estimation (version 90.2) was provided by Gasser and Kohler (Gasser et al. 1984). The program for the structural average curve of the XYY and control boys was supplied by Gasser (Gasser, Kneip, Ziegler, Largo and Prader 1990). Further processing of statistical analyses was performed via the program package GROSTAT II (Rasbash and Pan 1990).
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Growth during puberty in X Y Y boy
581
2.5. Definition o f parameters Age at zero acceleration at the onset of the pubertal growth spurt (PS) T6 (minimal pre-spurt height velocity). T8 Age at the second zero acceleration in the PS (maximal peak height velocity PHV). T9 Age of maximal deceleration in the PS in the OK method; the age at return to minimal pre-spurt velocity in the VADK method (the end of the PS). VT6 Value of velocity at T6. VT9 Value of velocity a t / ' 9 . HT9 Value of height at T9. Duration of the PS. T9_6 Speak Increase in the area under the velocity curve resulting from the PS (Figure
1).
20
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I
I
I
I
I
I
18
i
16 L_
14
\
E o c m
12
C
10
m
i
u 0 @
>
8 6 4 2 I
0 0
2
4
6
8
10
12
A g e in y e a r s
Figure 1. Heightvelocitycurve of an XYY boy.
14
16
18
20
S.G. Ratcliffe et al.
582
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
2.5. Methods The e s t i m a t i o n used for fitting distance curves is the kernel o f o r d e r (0 4) with o p t i m a l b a n d w i d t h d e t e r m i n e d a d a p t i v e l y f r o m the d a t a as in G a s s e r et al. (1984). S u p p o s e H(ti) ( i = 1 . . . . . n) indicates the height m e a s u r e d at age t i a n d /-I (tj) ( j = 1 . . . . . m) denotes e s t i m a t e d distance b y t h e OK m e t h o d at age tj with a fixed interval t5 (tj - tj_ l = ~5y e a r j = 2 . . . . . m). Velocity a n d acceleration directly were o b t a i n e d f r o m the a b o v e e s t i m a t e d distance curve. S u p p o s e 17 a n d `4 indicate velocity a n d acceleration to be e s t i m a t e d at intervals o f At year respectively, the l ? a n d .4 at m i d p o i n t s o f At are e s t i m a t e d b y the following a p p r o a c h (VADK) ( P a n a n d Ratcliffe 1992):
17( tJ2tJ-k__) = I:I(tj)- ISI(tj.k))/At
j=l+k
.....
m
A(tj) = (/-I(tj + k) - 2/-t(tj) + I~I(ti_k))/(At) 2
j=l+k
.....
m-k
where At=K>( 6. I n this s t u d y we set 6 = O. 1 y e a r a n d k = 10 so t h a t the velocity a n d acceleration curves are e s t i m a t e d at 1 y e a r intervals (At = 1.0 year). E s t i m a t i o n o f the p a r a m e t e r Speak in F i g u r e 1 is as follows,
Speak= SABC~-- SAB~e where
SABCDE =H T 9 - H T 6 SnBDe = (T9 - T6) × VT6 3. Results In o r d e r to assess the validity o f the new m e t h o d (VADK) we have c o m p a r e d the results o b t a i n e d for the characteristic p a r a m e t e r s o f the PS f r o m the E d i n b u r g h controls with t h o s e o b t a i n e d f r o m the Zurich L o n g i t u d i n a l study using the O K m e t h o d (Gasser et aL 1985) a n d find only small differences (Table 1). T h e E d i n b u r g h controls measurements have also been analysed by the graphical heuristical m e t h o d (Tanner, Whitehouse, M a r u b i n i a n d Resele 1976) b o t h series o f c o m p a r i s o n s being shown in Table 1. Table 1. Comparison of parameters by method in control boys. Age (years)
Height (cm)
Velocity (cm/year)
N
Minimum velocity T6
Gasser VADK Tanner
10-9 (1.1) 11.3 (1.0) 11-6 (1.0)
143.6 (6"8) 143.8 (8.0) 145.2 (7.9)
4.3 (0.5) 4.7 (0.7) 4.7 (0.7)
45 16 16
Maximum velocity T8
Gasser VADK Tanner
13.9 (0"9) 13-8 (1.2) 13.7 (1-3)
161.4 (6.6) 159.6 (7.6) 159.2 (7.0)
8.3 (0.8) 8"9 (1-3) 9"6 (1-4)
45 16 16
Maximum deceleration T9
Gasser VADK
15.4 (0"9) 15-2 (1.2)
172.4 (6"6) 170-1 (7-5)
5.0 (0.6) 4.7 (0-7)
45 16
Duration of pubertal spurt
Gasser VADK
4.5 (0.6) 3.9 (0.5)
T9_6
Pubertal height gain HT9_6
Gasser VADK
45 16 28-8 (4.0) 26- 3 (3" 2)
Values are expressed as mean and standard deviation in brackets.
45 16
Growth during puberty in X Y Y boy
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Table 2.
583
Comparison of XYY and control boys parameters. XYY n=8
Controls n = 16
Age of onset of PS (years) Velocity at onset of PS (cm/year) Height at onset of PS (cm)
11.5 (1"3) 4.9 (0.8) 151.4 (6.8)I
11.3 (1-0) 4.7 (0-7) 143.8 (8-0)
Age at PHV (years) PHV (cm/year) Height at PHV (cm)
14.2 (1.0) 10.3 (0- 7)t 170.5 (5.1):~
13.8 (1.2) 8" 9 (1.3) 159-6 (7.6)
Age at the end of PS (years) Velocity at the end of PS (cm/year) Height at the end of PS (cm)
15.7 (l .0)
15-2 (1-2)
4.9 (0" 8) 183.2 (4.2):~
4.7 (0.7) 170.1 (7.5)
Duration of PS Height gain during PS (cm) Peak area (cm2) Height at age 18 years
4.2 31.8 10.7 188-1
3- 9 26-3 8-2 175.1
(0- 5) (5-0)~ (2.3)~" (3"8)t
"~p < 0 . 0 5 and ~ p < 0 . 0 1 . (Analysis of variance on the normal scores of the parameters.)
20
,-
>b
I
I
I
I
I
I
I
I
I
18
XYY
16
XY
14
\
E c
•-
12 10
_• 8 e 4 2 0
0
I
I
I
I
I
I
I
I
I
2
4
6
8
10
12
14
16
18
Age Figure 2.
in y e a r s
Structural average height velocity in XYY and XY boys.
20
(0" 5) (3.2) (1.8) (7.7)
584
S.G. Ratcliffe et al. Table 3.
XYY XY
Mean height of parents.
8 16
Father (cm)
Mother (cm)
174.1 (5.4) 172-8 (6.0)
162.8 (4.2) 161.0 (6.1)
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Values are expressed as mean standard deviation.
With the VADK method the onset of the pubertal spurt T6 occurred at age 11.3 years which was 0.4 years later than found using the OK method. The height of both groups at this stage was virtually identical, and velocity at 4.7 cm/year using the VADK was close to that of 4.3 cm/year by the OK method. Peak height velocity, T8, occurred with similar timing and intensity, although the Zurich boys were 1.8 cm taller at this stage, and at final height. At all points the VADK method produced a little less smoothing than the OK method. Similarly Tanner's graphical method, obtained a PHV of 9.6 cm/year, compared with 8-3 cm/year by the OK method and 8.9 cm/year by VADK. XYY boys results are shown in Table 2 in comparison with the Edinburgh controls. XYY boys are 7.6 cm taller (p < 0.05) at the onset of the PS, 10.9 cm taller (p < 0.01) at PHV and 13-0cm taller (p
1992, VOL. 19, NO. 6, 5 7 9 - 5 8 7
Growth during puberty in the XYY boy S.G. RATCL1FFE~',~H. PAN§and M. MCKIEt tMedical Research Council Human Genetics Units, Edinburgh, UK SDepartment of Growth and Development, Institute of Child Health, London, UK §Department of Mathematics, Statistics and Computing, Institute of Education, London, UK
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Received 30th July 1991; revised 23rd October 1991
Summary. The availability of a cohort of eight unselected XYY boys identified by newborn cytogenetic screening has enabled their growth to be studied longitudinally in comparison with controls from the same population. While no difference had been found in dimensions at birth, increased height velocity in childhood resulted in the XYY boys being 7.6 cm taller at the onset of their pubertal growth spurt. Increased intensity of growth at puberty with a peak height velocity of 10-6cm/year contributed to their adult height of 188.1 cm. XYY boys showed twice the male-female difference in height implying that genes on the Y chromosome exert a quantitative effect on the sexual dimorphism of growth.
1. Introduction Tall stature has been a consistent feature of the descriptions of men with an additional Y chromosome since the first report of an XYY sex chromosome constitution in the human (Sandberg, Koepf, Ishihara and Hauschka 1961) in which the man's height was 183 cm. Following a number o f single case reports, the first major group of XYY men were described in the maximum security hospital in Scotland (Jacobs, Brunton, Melville, Brittain and McClemont 1965); they had a mean height of 185 cm. Most subsequent surveys of mental-penal institutions (Hook 1973) as well as the population based studies (Zeuthen and Nielsen 1973, Noel, Duport, Revil, Dussuyer and Quack 1974, Witkin, Mednick, Schulsinger, Bakkestrom, Christiansen, Goodenongh, Hirschhorn, Lundsteen, Owen, Philip, Rubin and Stocking 1976, Dorus, Dorus, Telfer, Litwin and Richardson 1976) investigated only those males with heights above 183 cm thus introducing a bias in the available records of height of XYY men, and led to an expectation of invariably increased stature. However, review of the literature describing 117 XYY men revealed a height range of 169-223 cm (Ratcliffe 1981). While the evidence implies that generally the second Y chromosome does increase height it would appear that this effect can be negated by adverse environmental factors pre- and post-natally (Faed, Lamont, Morton, Robertson and Smail 1978). As the use of chromosomal analysis in the differential diagnosis of short stature in boys is less frequent than in girls, other short XYY boys may have remained undiagnosed. It has been noted that XYY men are taller than their fathers (Noel et aL 1974) but it is not known whether the parent-offspring correlation is retained in XYY individuals, as it is in conditions such as Klinefelter and Turner syndromes (Brook, Gasser, Werder, Prader, Vanderschueren-Lodewykx 1977). Most of the literature on the growth and body proportions of XYY individuals relates to adults (Milne, Lauder and Price 1974, Alvesalo, Osborne and Kari 1975, Varrela and Alvesalo 1985) as few children with the XYY karotype were identified until the inception of newborn cytogenetic surveys. This resulted in cohorts whose 0301-4460/92 $3.00 © 1992Taylor & Francis Ltd.
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
580
S.G. Ratcliffe et al.
growth could be studied longitudinally, and who were free from selection bias both in height and behaviour. The size of the XYY infant at birth has been shown not to differ from that of chromosomally normal males, both from the collated literature (Chen, Chan and Falek 1971) and from XYY infants identified by cytogenetic screening of consecutive liveborn infants (Ratcliffe 1985). A longitudinal study of a cohort of 14 XYY boys from the above cytogenetic survey has shown height velocity to be significantly increased throughout childhood from age 4 years (Ratcliffe, Butler and Jones 1991). In this report we examine the growth during puberty of eight XYY boys from the survey. We use the optimal kernel (OK) estimation (Gasser, Kohler, Muller, Kneip, Largo, Molinari and Prader 1984) to obtain smoothed distance curves of these individuals and follow this with a new method (VADK)--deriving Velocity and Acceleration from the Distance curve fitted by the Kernel estimation (Pan and Ratcliffe 1991). Characteristic parameters of pubertal growth were then obtained and compared with those of chromosomally normal boys from the same newborn population, studied with the same methods.
2. Subjects and methods 2.1. Subjects Subjects from whom growth measurements have been obtained are: (a) Eight XYY boys identified by cytogenetic screening of consecutive liveborn infants who were at least 18 years of age. Three boys were members of dizygous twin pairs; two pairs of twins were identified in the main survey and the third set in the survey of twin births (Ratcliffe and Paul 1986). (b) The oldest 16 boys from the control group (n = 99 boys) of the Edinburgh Longitudinal Study. These children are known to be chromosomally normal as they were born at a time when the Medical Research Council was conducting the newborn cytogenetic survey. 2.2. Measurements Anthropometric measures were taken by S.G.R. who was trained in measurement techniques by R.H. Whitehouse of the Department of Growth and Development, Institute of Child Health, University of London. The children attended a growth clinic 3-monthly during the first year of life, and twice-yearly thereafter. A range of measures was taken, including height, Using the equipment and techniques identical to those used in the Harpenden study of growth (Tanner 1962). 2.3. Editing Gross errors had been corrected in a previous investigation (Butler, McKie and Ratcliffe 1990). Children were excluded from the analysis if two consecutive measurements were missing after age 6 years.
2.4. Computations Computations were done on a PC/AT compatible computer in Institute of Education, University of London. The program of kernel estimation (version 90.2) was provided by Gasser and Kohler (Gasser et al. 1984). The program for the structural average curve of the XYY and control boys was supplied by Gasser (Gasser, Kneip, Ziegler, Largo and Prader 1990). Further processing of statistical analyses was performed via the program package GROSTAT II (Rasbash and Pan 1990).
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Growth during puberty in X Y Y boy
581
2.5. Definition o f parameters Age at zero acceleration at the onset of the pubertal growth spurt (PS) T6 (minimal pre-spurt height velocity). T8 Age at the second zero acceleration in the PS (maximal peak height velocity PHV). T9 Age of maximal deceleration in the PS in the OK method; the age at return to minimal pre-spurt velocity in the VADK method (the end of the PS). VT6 Value of velocity at T6. VT9 Value of velocity a t / ' 9 . HT9 Value of height at T9. Duration of the PS. T9_6 Speak Increase in the area under the velocity curve resulting from the PS (Figure
1).
20
i
I
I
I
I
I
I
I
I
18
i
16 L_
14
\
E o c m
12
C
10
m
i
u 0 @
>
8 6 4 2 I
0 0
2
4
6
8
10
12
A g e in y e a r s
Figure 1. Heightvelocitycurve of an XYY boy.
14
16
18
20
S.G. Ratcliffe et al.
582
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
2.5. Methods The e s t i m a t i o n used for fitting distance curves is the kernel o f o r d e r (0 4) with o p t i m a l b a n d w i d t h d e t e r m i n e d a d a p t i v e l y f r o m the d a t a as in G a s s e r et al. (1984). S u p p o s e H(ti) ( i = 1 . . . . . n) indicates the height m e a s u r e d at age t i a n d /-I (tj) ( j = 1 . . . . . m) denotes e s t i m a t e d distance b y t h e OK m e t h o d at age tj with a fixed interval t5 (tj - tj_ l = ~5y e a r j = 2 . . . . . m). Velocity a n d acceleration directly were o b t a i n e d f r o m the a b o v e e s t i m a t e d distance curve. S u p p o s e 17 a n d `4 indicate velocity a n d acceleration to be e s t i m a t e d at intervals o f At year respectively, the l ? a n d .4 at m i d p o i n t s o f At are e s t i m a t e d b y the following a p p r o a c h (VADK) ( P a n a n d Ratcliffe 1992):
17( tJ2tJ-k__) = I:I(tj)- ISI(tj.k))/At
j=l+k
.....
m
A(tj) = (/-I(tj + k) - 2/-t(tj) + I~I(ti_k))/(At) 2
j=l+k
.....
m-k
where At=K>( 6. I n this s t u d y we set 6 = O. 1 y e a r a n d k = 10 so t h a t the velocity a n d acceleration curves are e s t i m a t e d at 1 y e a r intervals (At = 1.0 year). E s t i m a t i o n o f the p a r a m e t e r Speak in F i g u r e 1 is as follows,
Speak= SABC~-- SAB~e where
SABCDE =H T 9 - H T 6 SnBDe = (T9 - T6) × VT6 3. Results In o r d e r to assess the validity o f the new m e t h o d (VADK) we have c o m p a r e d the results o b t a i n e d for the characteristic p a r a m e t e r s o f the PS f r o m the E d i n b u r g h controls with t h o s e o b t a i n e d f r o m the Zurich L o n g i t u d i n a l study using the O K m e t h o d (Gasser et aL 1985) a n d find only small differences (Table 1). T h e E d i n b u r g h controls measurements have also been analysed by the graphical heuristical m e t h o d (Tanner, Whitehouse, M a r u b i n i a n d Resele 1976) b o t h series o f c o m p a r i s o n s being shown in Table 1. Table 1. Comparison of parameters by method in control boys. Age (years)
Height (cm)
Velocity (cm/year)
N
Minimum velocity T6
Gasser VADK Tanner
10-9 (1.1) 11.3 (1.0) 11-6 (1.0)
143.6 (6"8) 143.8 (8.0) 145.2 (7.9)
4.3 (0.5) 4.7 (0.7) 4.7 (0.7)
45 16 16
Maximum velocity T8
Gasser VADK Tanner
13.9 (0"9) 13-8 (1.2) 13.7 (1-3)
161.4 (6.6) 159.6 (7.6) 159.2 (7.0)
8.3 (0.8) 8"9 (1-3) 9"6 (1-4)
45 16 16
Maximum deceleration T9
Gasser VADK
15.4 (0"9) 15-2 (1.2)
172.4 (6"6) 170-1 (7-5)
5.0 (0.6) 4.7 (0-7)
45 16
Duration of pubertal spurt
Gasser VADK
4.5 (0.6) 3.9 (0.5)
T9_6
Pubertal height gain HT9_6
Gasser VADK
45 16 28-8 (4.0) 26- 3 (3" 2)
Values are expressed as mean and standard deviation in brackets.
45 16
Growth during puberty in X Y Y boy
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Table 2.
583
Comparison of XYY and control boys parameters. XYY n=8
Controls n = 16
Age of onset of PS (years) Velocity at onset of PS (cm/year) Height at onset of PS (cm)
11.5 (1"3) 4.9 (0.8) 151.4 (6.8)I
11.3 (1-0) 4.7 (0-7) 143.8 (8-0)
Age at PHV (years) PHV (cm/year) Height at PHV (cm)
14.2 (1.0) 10.3 (0- 7)t 170.5 (5.1):~
13.8 (1.2) 8" 9 (1.3) 159-6 (7.6)
Age at the end of PS (years) Velocity at the end of PS (cm/year) Height at the end of PS (cm)
15.7 (l .0)
15-2 (1-2)
4.9 (0" 8) 183.2 (4.2):~
4.7 (0.7) 170.1 (7.5)
Duration of PS Height gain during PS (cm) Peak area (cm2) Height at age 18 years
4.2 31.8 10.7 188-1
3- 9 26-3 8-2 175.1
(0- 5) (5-0)~ (2.3)~" (3"8)t
"~p < 0 . 0 5 and ~ p < 0 . 0 1 . (Analysis of variance on the normal scores of the parameters.)
20
,-
>b
I
I
I
I
I
I
I
I
I
18
XYY
16
XY
14
\
E c
•-
12 10
_• 8 e 4 2 0
0
I
I
I
I
I
I
I
I
I
2
4
6
8
10
12
14
16
18
Age Figure 2.
in y e a r s
Structural average height velocity in XYY and XY boys.
20
(0" 5) (3.2) (1.8) (7.7)
584
S.G. Ratcliffe et al. Table 3.
XYY XY
Mean height of parents.
8 16
Father (cm)
Mother (cm)
174.1 (5.4) 172-8 (6.0)
162.8 (4.2) 161.0 (6.1)
Ann Hum Biol Downloaded from informahealthcare.com by V U L Periodicals Rec on 12/30/14 For personal use only.
Values are expressed as mean standard deviation.
With the VADK method the onset of the pubertal spurt T6 occurred at age 11.3 years which was 0.4 years later than found using the OK method. The height of both groups at this stage was virtually identical, and velocity at 4.7 cm/year using the VADK was close to that of 4.3 cm/year by the OK method. Peak height velocity, T8, occurred with similar timing and intensity, although the Zurich boys were 1.8 cm taller at this stage, and at final height. At all points the VADK method produced a little less smoothing than the OK method. Similarly Tanner's graphical method, obtained a PHV of 9.6 cm/year, compared with 8-3 cm/year by the OK method and 8.9 cm/year by VADK. XYY boys results are shown in Table 2 in comparison with the Edinburgh controls. XYY boys are 7.6 cm taller (p < 0.05) at the onset of the PS, 10.9 cm taller (p < 0.01) at PHV and 13-0cm taller (p
