Longitudinal growth and height velocity of Japanese children withDown’s syndrome

J Kimura1,2, K Tachibana3, K Imaizumi1, K Kurosawa1 and Y Kuroki1

Division of Medical Genetics1, Kanagawa Children’s Medical Center, Yokohama; Department of Pediatrics2, Graduate School ofMedical Sciences, Kyushu University, Fukuoka; Divisions of Endocrinology and Metabolism3, Kanagawa Children’s Medical Center,Yokohama, Japan

Kimura J, Tachibana K, Imaizumi K, Kurosawa K, Kuroki Y. Longitudinal growth and heightvelocity of Japanese children with Down’s syndrome. Acta Pædiatr 2003; 92: 1039–1042.Stockholm. ISSN 0803-5253

Aim: To determine the natural growth pattern of Japanese children with Down’s syndrome.Methods: Longitudinal height data of 85 patients (43 males, 42 females) from birth to final heightwere analyzed. Based on these data, semi-longitudinal standard growth curves and height velocitycurves for Down’s syndrome were drawn.Results: The means� SD of final height of males andfemales with Down’s syndrome were 153.2� 5.6 and 141.9� 4.2 cm, respectively. They were�3.0 SD and�2.8 SD for Japanese standards. Mean peak height velocities were 8.9 and 7.5 cmy�1, and the ages at peak height velocity were 11.6 and 10.2 y for males and females, respectively.

Conclusion: The mean height of patients with Down’s syndrome was around�2 SD for normalchildren before puberty. Their pubertal growth spurt starts about 1 y earlier and their peak heightvelocity was about 1.3–1.4 cm shorter than for normal children.

Key words: Down’s syndrome, growth curve, height velocity

K Tachibana, Divisions of Endocrinology and Metabolism, Kanagawa Children’s Medical Center,Mutsukawa 2-138-4, Minani-ku, Yokohama 232-8555, Japan (Tel. �81 45 711 2351, fax. �81 45742 7821, e-mail. ktachiba@pp.iij4u.or.jp)

Growth standards based on cross-sectional data areuseful for the evaluation of growth and health ofchildren. However, cross-sectional standards do notrepresent the actual growth pattern of individualchildren, especially during puberty. The ages at thestart of the pubertal growth spurt and at the peak heightvelocity vary in each individual, and this phasedifference distorts the average height and heightvelocity curves based on cross-sectional data. There-fore, it has been emphasized that longitudinal growthstandards are adequate for sequential assessment of thegrowth of children.

Down’s syndrome is the most prevalent unbalancedchromosome aberration, with an incidence of 1 per 800–1000 livebirths. Short stature, especially after puberty,is one of the major features of Down’s syndrome.Although several cross-sectional growth charts specificfor Down’s syndrome are available in some countries(1–8), only a few longitudinal height and heightvelocity standards of children with Down’s syndromehave been reported (3, 5, 6).

The aim of this study was to determine the naturalgrowth pattern of Japanese children with Down’ssyndrome.

Subjects and methods

The subjects were 85 children (43M, 42F) with Down’ssyndrome who were born between 1973 and 1985 andfollowed in Kanagawa Children’s Medical Center.Those who were followed until reaching their finalheight and lived with their family were included. Finalheight was designated as the height when annual growthbecame less than 1 cm. All children with mosaicism andthose with other chromosomal aberrations or complica-tions that might affect natural growth (congenital heartdefects, gastrointestinal malformations, thyroid dys-function, leukemia and epilepsy) were excluded.

Height or length had been measured every 3 mobefore 1 y, every 6 mo between 1 and 6 y, and every 1 yover 6 y of age at hospital visits. Height data wereretrospectively obtained from medical records. Theheight data were available at all these time points forevery child.

The height data of a child were plotted on a graphsheet and a smooth growth curve for that particularchild was drawn by an eye-fitting technique using aflexible lead spline as a guide. Then the heights at every3 mo of age for each child were read from the individual

2003 Taylor & Francis. ISSN 0803-5253

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DOI 10.1080/08035250310004306

curve. For cross-sectional analysis, the mean andstandard deviation (SD) of heights at each age werecalculated using all these data.

The difference in height between two time points12 mo apart was defined as the height velocity at thetime point intermediate between the two. The heightvelocity (cm y�1) was calculated at every 3 mo of agefor each child.

The mean and SD of final heights, the age and theheight at the start of growth spurt, the age at peak heightvelocity, and peak height velocity were calculated andwere compared with those of the Japanese standards (9).

Student’st-test was used for statistical analysis.

ResultsThe mean and SD of the final heights, the age and theheight at the start of growth spurt, the age at peak heightvelocity, and the peak height velocity are shown in

Table 1. For comparison, these data for normal childrenof a similar generation (born between 1966 and 1970)are also shown.

Children with Down’s syndrome entered the pubertalgrowth spurt earlier and their peak height velocitieswere slower than for normal children. The mean finalheights were 153.2 and 141.9 cm for males and females,respectively, and�3.0 SD and�2.8 SD for Japanesestandards.

The semi-longitudinal standard growth curves forDown’s syndrome based on height data are shown inFigs 1 and 2.

The height velocity curves based on the mean heightvelocity at every 3 mo of age are shown in Figs 3 and 4.Although the height velocity data of each child arebased on longitudinal data, these curves do not representthe actual growth pattern of individual children, sincethe tempo of puberty was not taken into consideration.Since the age at peak height velocity differs in eachindividual, the pubertal peaks of Figs 3 and 4 areblunted. Longitudinal height velocity curves showing

Table 1. Final height, age and height at start of growth spurt, age at peak height velocity, and peak height velocity of children with Down’ssyndrome and Japanese standards (9).

Boys Girls

Down’s syndrome Standards Down’s syndrome Standards(n = 43) (n = 439) (n = 42) (n = 483)

Final height (cm) 153.2� 5.6 169.1� 5.9* 141.9� 4.2 157.7� 4.9*Age at start of growth spurt (y) 9.9� 1.3 11.1� 1.1* 8.8� 1.1 9.4� 1.2*Height at start of growth spurt (cm) 124.3� 6.7 136.4� 7.0* 116.8� 5.5 130.6� 7.3*Age at peak height velocity (y) 11.7� 1.2 13.0� 1.0* 10.2� 1.1 11.2� 1.1*Peak height velocity (cm y�1) 9.0� 1.4 10.3� 1.0* 7.3� 0.8 8.7� 1.2*

Data are shown as mean� SD.* p � 0.01 (Student’st-test).

Fig. 2. Semi-longitudinal growth curve for girls with Down’ssyndrome. Dotted lines: normal Japanese girls.

Fig. 1. Semi-longitudinal growth curve for boys with Down’ssyndrome. Dotted lines: normal Japanese boys.

1040 J Kimura et al. ACTA PÆDIATR 92 (2003)

actual growth patterns were prepared using the follow-ing correction.

For the period younger than 5 y, the mean of theheight velocity was used. For the period older than 5 y,the data of height velocity for each child were shiftedhorizontally as age at peak height velocity came tocoincide with the mean of that parameter (11.7 y formales and 10.2 y for females) and mean and SD werecalculated.

The corrected longitudinal height velocity curves are

shown in Figs 5 and 6. These curves show steeper peaksof the pubertal spurt and seem to reflect actual growth.

Tables of mean and SD of height and corrected heightvelocity are available from the author upon request.

DiscussionThe birth length of children with Down’s syndrome is

Fig. 3. Height velocity curve for boys with Down’s syndrome. Dottedlines: normal Japanese boys.

Fig. 4. Height velocity curve for girls with Down’s syndrome. Dottedlines: normal Japanese girls.

Fig. 5. Corrected height velocity curve for boys with Down’ssyndrome. Dotted lines: normal Japanese boys.

Fig. 6. Corrected height velocity curve for girls with Down’ssyndrome. Dotted lines: normal Japanese girls.

ACTA PÆDIATR 92 (2003) Longitudinal growth in Japanese Down’s syndrome 1041

almost same as that of normal children, but their heightvelocity is already slow during infancy and the meanheight reaches�2 SD of Japanese standards before 3 y.Thereafter, the mean height for Down’s syndromefollows about�2 SD until pubertal age. This is similarto previous reports (2, 3, 6), and indicates that thegrowth pattern before puberty is a characteristic ofDown’s syndrome without racial differences.

At pubertal age, the growth spurt starts earlier and at ashorter height than in normal children. In addition, thepeak height velocity is lower, and as a result the finalheight is about�3 SD of Japanese standards in bothgenders. Previous studies reported that the heightvelocity of adolescents with Down’s syndrome wasblunted (1, 5–7, 10, 11). This might be because the tempoof puberty was not taken into consideration. In this study,height velocity curves based on raw mean height velocitydata were also blunted during adolescence, but aftercorrection for tempo of the pubertal growth spurt theyshowed almost the same shape as Japanese standards (9),except that the growth spurt began earlier and its peakwas smaller. These curves are expected to reflectindividual growth pattern appropriately. Kuroki et al.reported that the age at the start of the growth spurt wassimilar to that for normal controls (3), contrary to thefinding of the present study, perhaps because theyincluded individuals with some complications.

The height velocity of Down’s syndrome before thegrowth spurt is almost constant. It differs from that fornormal children (9) and children with Turner’s syn-drome (12, 13); their growth velocity gradually de-creases with age before the growth spurt starts. Thepattern of growth velocity of children with Down’ssyndrome before the growth spurt was similar to that ofchildren with growth hormone deficiency (14), Laronsyndrome (15) and achondroplasia (16). The cause ofshort stature of children with these conditions isdysfunction of growth hormone–insulin-like growthfactor-1 (GH-IGF-1) axis function or the growth plate,the target tissue of IGF-1. Previous studies reported thatserum levels of IGF-1 in individuals with Down’ssyndrome were lower than in normal children (17, 18).The present data suggest the hypothesis of GH-IGF-1axis dysfunction in Down’s syndrome.

Since children with Down’s syndrome enter thepubertal growth spurt earlier, it is very likely that theyhave early puberty. There are reports showing that girlswith Down’s syndrome have earlier menarche than inthe general population (19, 20). Unfortunately, theappearance of secondary sexual characteristics couldnot be examined in this study, since hospital visits atpubertal age occurred only once a year and the accurateage of their appearance could not be determined.

This study determined the semi-longitudinal growthcurve and height velocity curve of Japanese childrenwith Down’s syndrome without major complications.These are useful for evaluating the growth and health ofa child with Down’s syndrome. In addition, they are

useful for evaluating the effects of congenital mal-formations (congenital heart defects, gastrointestinalmalformations) and pathological conditions such asthyroid dysfunction, leukemia and epilepsy on growth,and the effects of treatment on these conditions.

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Received Sept. 26, 2002; revisions received Apr. 24, 2003; acceptedMay 13, 2003

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