Growth Monitoring
One of the most well-known guidelines for children with achondroplasia was published in 2005 in the American Academy of Pediatrics Journal by Trotter T and Hall J. The full document, that can be read here, advises pediatricians on how counsel parents of children with achondroplasia, how to prevent complications, and, most importantly of all, how to monitor their health while they are growing [1].
From birth to adulthood, many parameters are monitored for every child such as reflexes and growth rate. The latter is monitored by plotting the child's height into a growth chart. By plotting the height of the child and comparing to the typical growth rate of other children with achondroplasia, it is possible to see if a child with achondroplasia is growing at the expected rate and the impact of growth-promoting treatments can be evaluated. When a child's growth falls outside these charts, it's possible that there may be an underlying condition or complication that needs to be looked into [1-4].
Although Dr. Horton developed growth charts in 1978, it is known that there are variations in mean population parameters (such as height, weight and head circumference) between countries. It is also known that the population isn't stagnant, changing through time, since the standard growth curves for the average height population were updated recently (for instance, in the USA they were updated by the CDC in 2000, using the World Health Organisation's standards) [5-7]. For these reasons recently new growth charts for most of these parameters for children with achondroplasia have been developed for the American population by Dr. Hoover-Fong and her team, for the Argentinian population by Dr. del Pino and her team and for the Australian population by Dr. Tofts and her team [2-4].
Although Dr. Horton developed growth charts in 1978, it is known that there are variations in mean population parameters (such as height, weight and head circumference) between countries. It is also known that the population isn't stagnant, changing through time, since the standard growth curves for the average height population were updated recently (for instance, in the USA they were updated by the CDC in 2000, using the World Health Organisation's standards) [5-7]. For these reasons recently new growth charts for most of these parameters for children with achondroplasia have been developed for the American population by Dr. Hoover-Fong and her team, for the Argentinian population by Dr. del Pino and her team and for the Australian population by Dr. Tofts and her team [2-4].
These charts (available below) were made to monitor all parameters that have clinical relevance from birth to adulthood: height, weight, occipital-frontal circumference, (OFC, can be interpreted as head circumference), body mass index (BMI) and foramen magnum diameter. The charts currently available can be consulted by clicking the buttons further below.
The data of linear growth rate (height-for-age charts) has a major relevance on the identification of possible underlying conditions as well as on increasing knowledge on the natural evolution of achondroplasia and with this, facilitate new medicines development. Also, new drug development often uses linear growth as a primary output for the drug's effect, which needs accurate growth curves for comparison [2].
Weight-for-age charts and BMI have an important role in health monitoring in a clinical setting on children and adolescents with achondroplasia. On the one hand, obesity rates in achondroplasia are 3 to 8 times higher than the general population, and since there is also an increased risk of cardiovascular disease-related death, which is also worsened by obesity, warranting for nutritional counseling [8, 9]. On the other hand there's a possibility for failure to thrive, especially during early childhood, can be a sign of an underlying condition, such as cervicomedullary compression, which warrants neurosurgical assessment [10].
The data of linear growth rate (height-for-age charts) has a major relevance on the identification of possible underlying conditions as well as on increasing knowledge on the natural evolution of achondroplasia and with this, facilitate new medicines development. Also, new drug development often uses linear growth as a primary output for the drug's effect, which needs accurate growth curves for comparison [2].
Weight-for-age charts and BMI have an important role in health monitoring in a clinical setting on children and adolescents with achondroplasia. On the one hand, obesity rates in achondroplasia are 3 to 8 times higher than the general population, and since there is also an increased risk of cardiovascular disease-related death, which is also worsened by obesity, warranting for nutritional counseling [8, 9]. On the other hand there's a possibility for failure to thrive, especially during early childhood, can be a sign of an underlying condition, such as cervicomedullary compression, which warrants neurosurgical assessment [10].
Lastly, monitoring changes in head circumference can detect growth outside the norm or rapid increases in size, can also help monitor for potential complications, such as hydrocephalus which is more common in the first 2 years of life and may indicate other underlying conditions, such as compression of the cervical spine at the foramen magnum [3, 11]. Because of this last complication, and since it can be the cause of hydrocephalus and of a higher incidence of sudden infant death, foramen magnum diameter (FMD) must be monitored early for early intervention (if necessary) and prevention of sequelae from these complications [11, 12].
Click on the sections below to access the respective growth charts:
 |
 |
 |
 |
 |
Sources:
- Trotter, T.L. and J.G. Hall, Health Supervision for Children With Achondroplasia. Pediatrics, 2005. 116(3): p. 771-783. Available from: http://pediatrics.aappublications.org/content/pediatrics/116/3/771.full.pdf.
- Hoover-Fong, J., et al., A height-for-age growth reference for children with achondroplasia: Expanded applications and comparison with original reference data. American Journal of Medical Genetics Part A, 2017. 173(5): p. 1226-1230. Available from: http://dx.doi.org/10.1002/ajmg.a.38150.
- del Pino, M., V. Fano, and H. Lejarraga, Growth references for height, weight, and head circumference for Argentine children with achondroplasia. Eur J Pediatr, 2011. 170(4): p. 453-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/20938683.
- Tofts, L., et al., Growth charts for Australian children with achondroplasia. Am J Med Genet A, 2017. 173(8): p. 2189-2200. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28599087.
- Schonbeck, Y., et al., The world/'s tallest nation has stopped growing taller: the height of Dutch children from 1955 to 2009. Pediatr Res, 2013. 73(3): p. 371-377. Available from: http://dx.doi.org/10.1038/pr.2012.189.
- CDC. Clinical Growth Charts. Growth Charts 2009 [cited 2017 15/05]; Available from: https://www.cdc.gov/growthcharts/clinical_charts.htm.
- Horton, W.A., J.G. Hall, and J.T. Hecht, Achondroplasia. The Lancet, 2007. 370(9582): p. 162-172. Available from: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(07)61090-3/fulltext.
- Hoover-Fong, J.E., et al., Age-appropriate body mass index in children with achondroplasia: interpretation in relation to indexes of height. Am J Clin Nutr, 2008. 88(2): p. 364-71. Available from: http://ajcn.nutrition.org/content/88/2/364.long.
- Poirier, P., et al., Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism. Circulation, 2006. 113(6): p. 898-918. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16380542.
- Hoover-Fong, J.E., et al., Weight for age charts for children with achondroplasia. American Journal of Medical Genetics Part A, 2007. 143A(19): p. 2227-2235. Available from: http://dx.doi.org/10.1002/ajmg.a.31873.
- Ireland, P.J., et al., Optimal management of complications associated with achondroplasia. The Application of Clinical Genetics, 2014. 7: p. 117-125. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4104450/.
- Hecht, J.T., et al., Growth of the foramen magnum in achondroplasia. Am J Med Genet, 1989. 32(4): p. 528-35. Available from: http://onlinelibrary.wiley.com/doi/10.1002/ajmg.1320310314/abstract.
