How to Cite this Article: Afifi HH, Aglan MS, Zaki ME, Thomas MM, Tosson AMS. 2012. Growth charts of Down syndrome in Egypt: A study of 434 children 0–36 months of age. Am J Med Genet Part A 158A: 2647–2655.
Growth charts of Down syndrome in Egypt: A study of 434 children 0–36 months of age†
Article first published online: 18 JUL 2012
Copyright © 2012 Wiley Periodicals, Inc.
American Journal of Medical Genetics Part A
Special Issue: SPECIAL ISSUE: GROWTH CHARTS IN GENETIC SYNDROMES
Volume 158A, Issue 11, pages 2647–2655, November 2012
How to Cite
Afifi, H. H., Aglan, M. S., Zaki, M. E., Thomas, M. M. and Tosson, A. M.S. (2012), Growth charts of Down syndrome in Egypt: A study of 434 children 0–36 months of age. Am. J. Med. Genet., 158A: 2647–2655. doi: 10.1002/ajmg.a.35468
- Issue published online: 17 OCT 2012
- Article first published online: 18 JUL 2012
- Manuscript Accepted: 13 APR 2012
- Manuscript Received: 27 NOV 2011
- Down syndrome;
- growth charts;
The aim of the study was to construct new reference growth charts for weight, length and head circumference of Egyptian children with Down syndrome (DS) from birth to 36 months of age. These specific charts may be used by health professionals involved in medical, physical and developmental care of Egyptian children with Down syndrome. The study included 434 children with non-disjunction trisomy 21, 0–36 months of age. They were 54.4% males and 45.6% females and had no concomitant chronic disease (congenital heart disease, gastrointestinal malformations, hypothyroidism, and blood disorders). Overall, 1,955 observations were performed of weight, length and head circumference. The data for each sex were divided into 37 different age groups with 1-month intervals. All measurements were taken using standardized equipments and following the international recommendations. Values were statistically analyzed and growth curves were plotted as means and standard deviations (SD). Growth measurements evaluated in all age groups of both sexes were significantly lower than those of the controls. There was a gender difference in weight, length and head circumference, males with Down syndrome had higher values. In conclusion, we suggest that these new growth charts specific for Down syndrome children may be used in optimizing direct Egyptian DS children care and in providing anticipatory guidance in term of optimal physical growth and early detection of hidden factors affecting growth. © 2012 Wiley Periodicals, Inc.
Down syndrome (DS) is the most frequent chromosomal disorder, with an incidence of about 1/600 live births in Egypt [Temtamy et al., 1998]. It is associated with intellectual disability, congenital malformations (especially of the heart), dysmorphic features, and dysfunction of several other organs [OMIM, 2011]. Short stature is a characteristic feature of DS. Growth retardation of DS individuals starts prenatally. After birth, the growth velocity is most reduced between 6 months to 3 years [Sara et al., 1983; Cronk et al., 1988]. Growth charts specific for children with DS are important tools for routine medical follow-up, as well as early identification of pathological causes of growth retardation, and monitoring of growth promoting treatments. Growth charts for Down syndrome are available from different countries, for example, Italy, USA, Denmark, Sweden, Portugal, France, UK and Ireland and Saudi Arabia [Piro et al., 1990; Palmer et al., 1992; Cremers et al., 1996; Toledo et al., 1999; Fernandes et al., 2001; Myrelid et al., 2002; Styles et al., 2002; Al Husain, 2003]. Comparing these DS growth charts reveals differences among the various populations.
The goal of this study is to provide new growth charts for weight, length, and head circumference for Egyptian DS infants from birth to 36 months of age.
MATERIALS AND METHODS
The study was carried out on patients referred to the outpatient clinic of the Clinical Genetics Department, National Research Centre, Cairo, Egypt, between January 2010 and September 2011. Their parents gave written informed consent to the study. The study was performed in accordance to the Declaration of Helsinki protocols and approved by the local institutional review boards.
Present data are based on 1,955 observations of 434 patients with Down syndrome. They were 236 males (54.4%) and 198 females (45.6%). The referred patients were all Egyptians, coming from different areas of Egypt. None of the patients were institutionalized. To avoid any patient being over represented in the dataset, not more than two measures (1 year apart) were included for any patient over the period of the study. The control group consisted of 3,950 healthy male and female Egyptian children, who had normal size at birth, no malformation, no chronic medical conditions and no dysmorphic facial findings. Controls were divided into monthly age groups, from birth to 36 months. Each age group consisted of at least 100 infants/children (50 males and 50 females).
Each patient was subjected to pedigree analysis, meticulous clinical examination and anthropometric measurements. Subjects with gestational age <38 weeks were not included in the study. Chromosomal analysis by G-banding technique, echocardiography, abdominal ultrasonography, complete blood picture and complete thyroid profile were done to confirm the provisional diagnosis and detect any dysfunction or abnormality. Patients with mosaic trisomy 21 or translocation were excluded from the study, as well as patients with abnormal abdominal findings, thyroid dysfunction or blood abnormality.
Growth measurements (weight, length, and head circumference) were taken by two trained physicians. Another person assisted with alignment and immobilization of the patient during measurements. All anthropometric measurements were attempted following the recommendations of the International Biological Publications, using standardized equipments [Hiernaux and Tanner, 1969; Hall et al., 1989]. They were recorded as the mean of three accepted consecutive readings.
Body weight was taken, using Seca scale approximated to the nearest 0.01 kg with minimal clothes for which no correction was made. Length was measured using an infantometer and approximated to the nearest 0.1 cm. An accurate head circumference measurement is produced by placing a non-stretchable tape around the mid-forehead and most prominent portion of the occiput in such a way that the maximum circumference is obtained. Comparison between Egyptian DS patients and normal Egyptian controls was performed.
Subjects were divided into male and female groups and sub-grouped into age groups (1 month apart), ranging from birth to 36 months. Means and standard deviation (SD) of evaluated growth measurements were calculated for each age and sex separately. They were graphically smoothed using polynomial fitting equation and plotted. Also, means for the three anthropometric measures comparing male and female Down syndrome patients with normal children were graphically plotted using polynomial equation for smoothing. Cubic splines, Kernel regression, and locally weighted regression methods were used for smoothing data. After comparison of these methods, locally weighted regression was selected and applied to the data set. Baker et al.  found that polynomial curves adequately represent growth pattern. We plotted growth curves of weight, length and head circumference from age 0–36 months with means and ±1 and 2 SDs.
Statistical analysis of data was carried out using SPSS software (version 16). Based on age and sex, the data were divided into monthly intervals from birth till 36 months. Means and SDs were calculated for the male and female groups. Student's t-test was used to compare the mean weight, length and head circumference at all age intervals between the two sexes, and between the two sexes of this study and the normal Egyptian controls. P-values <0.05 were considered significant.
Mean values and SD for weight, length and occipitofrontal circumference (OFC), with the corresponding mean growth curve of the Egyptian controls, were presented in Figures 1–3 for males and in Figures 4–6 for females. These figures show that the means of the DS patients are always below that of the controls.
At birth, comparison of weight, length and OFC values of males with DS versus females with DS, revealed higher values in males although not statistically significant (Table I). Males with DS had usually higher values of the different growth measurements than females with DS from birth till 36 months.
|Variables||Males with DS||Females with DS||P-value|
|Head circumference (cm)||34.90||1.3||33.60||2.5||0.5970|
Growth measurements of male and female DS patients were compared to Egyptian controls at birth, 12, 24, and 36 months. Statistical analysis revealed significant difference in all measurements of both sexes, where DS patients had lower values (Tables II and III).
|Head circumference (cm)|
|Head circumference (cm)|
Comparison of our growth charts with those previously reported in 2004 for Egyptian children with DS by Meguid et al. revealed that at birth the present data had slightly increased values in all anthropometric measurements, although not statistically significant (Table IV). Similar findings were noted when comparison was carried out for all anthropometric measurements in the other age groups for both sexes.
|Variables||Present study||Meguid et al., 2004||P-value for males||P-value for females|
|Males (mean)||Females (mean)||Males (mean)||Females (mean)|
|Head circumference (cm)||34.90||33.60||34.80||32.70||0.7959||0.2320|
Growth is an excellent marker of health status, both on individual and population level. It is useful and clinically important to use syndrome specific growth charts. Individuals with trisomy 21 have well documented growth retardation. Down syndrome may be associated with complicating disorders such as: celiac disease, hypothyroidism and growth hormone deficiency [OMIM, 2011]. These concomitant disorders may aggravate the growth retardation in DS individuals. The purpose of the study was to construct new reference growth charts for Egyptian Down syndrome individuals from birth to 36 months of age. These growth charts were created to meet the basic clinical need to monitor the physical development of young children with Down syndrome.
Statistically significant differences were detected between our patients and the Egyptian controls in all evaluated anthropometric measurements of both sexes and in all age groups. Patients with Down syndrome are characterized by an impaired growth, which has been documented in several reports [Palmer et al., 1992; Toledo et al., 1999; Fernandes et al., 2001; Myrelid et al., 2002; Al Husain, 2003; Meguid et al., 2004].
In agreement with previous studies there was a gender difference in weight, length and OFC measurements, males with Down syndrome tended to have higher but statistically non-significant values than females [Piro et al., 1990; Palmer et al., 1992; Fernandes et al., 2001; Myrelid et al., 2002; Meguid et al., 2004].
Sicilian males and females with DS had slightly lower mean values of height, length and OFC than the Egyptian DS children, especially in the first year of life [Piro et al., 1990]. When comparing the mean values of weight, length, and OFC of Egyptian and Portuguese children with DS [Fernandes et al., 2001], we confirmed that the results were similar up to 24 months of age, after which the Portuguese children presented slightly higher values, especially in length. Sweden and Egyptian children with DS had similar mean values of weight, length, and OFC up to 12 months, after which the Sweden males with DS showed higher values mainly in length and weight [Myrelid et al., 2002]. This may be partly due to genetic differences between the different studied populations and the time delay between various studies. Therefore, the development of updated specific DS growth charts for each population is justified.
Meguid et al.  published a report on growth curves of 350 patients with DS, 90 of them had congenital heart disorders. Their study was carried out between January 1999 and July 2001 and their charts were plotted as 3rd, 50th, and 97th centiles from 0–36 months for male and female patients. In comparison with Meguid et al. , there was a statistically non-significant increase in all anthropometric measurements in most age groups. This finding may be explained by the difference in sample selection criteria and the size of the studied groups. Also, the role of secular trend could not be ruled out. Our studied sample was larger (434 patients), carried out between January 2010 and September 2011, and included patients with non-disjunction trisomy 21 without cardiac affection. Also, our growth curves were plotted as means and ±2 SD, which is useful for detecting the degrees of deviation at extreme of distribution. Mei and Grummer-Strawn  supported the use of SD as a quality indicator for anthropometric data.
In conclusion, having new growth charts specific for Down syndrome individuals can help to discover any physical developmental delay and suggest the necessity of looking for concomitant diseases affecting growth. Growth charts for children with DS older than 36 months should be constructed.
We would like to thank the Department of Human Cytogenetics, National Research Centre, Cairo, Egypt, for performing the chromosomal analysis of the patients.
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