Russell-Silver Syndrome (RSS) is a rare growth disorder characterized by slow growth that begins before birth, known as intrauterine growth restriction, and continues through childhood. Affected individuals are born small for their gestational age and experience ongoing challenges in gaining weight and height. A primary tool in pediatrics is the growth chart, which plots metrics like height, weight, and head circumference against data from a large sample of children. For children with RSS, however, their unique growth pattern requires a specialized lens for accurate interpretation.
The Need for Specialized Growth Charts
Standard growth charts, like those from the Centers for Disease Control and Prevention (CDC) or the World Health Organization (WHO), are based on data from the general pediatric population. When a child with RSS is plotted on these standard charts, their measurements consistently fall far below the lowest percentile lines. This placement can create a misleading picture of “failure to thrive,” which can cause considerable anxiety for parents and may prompt physicians to order extensive and sometimes unnecessary medical investigations.
The growth pattern in children with RSS, while slow, is often predictable and follows a trajectory distinct from their peers. They experience restricted growth in the womb and, unlike many other children born small for their gestational age, do not have a period of “catch-up” growth after birth. A specialized chart is therefore needed to compare their growth not against typical children, but against their true peers: other children with Russell-Silver Syndrome.
Understanding the Russell-Silver Syndrome Growth Chart
A Russell-Silver Syndrome growth chart is a specialized clinical tool developed using growth data collected exclusively from a large group of children with a confirmed RSS diagnosis. Instead of appearing at the bottom of a standard chart, a child with RSS can be plotted against the growth curves of their peers, allowing for a meaningful assessment of their individual trajectory. For example, a child may fall on the 50th percentile on an RSS-specific chart, indicating they are growing at an average rate for a child with this condition.
Using the chart involves the same process as a standard one: a healthcare provider measures the child’s weight, height (or length for infants), and head circumference at regular intervals and plots these points on the graph. These specialized charts are not found in a general pediatrician’s office but are available through pediatric endocrinologists, geneticists, and patient support organizations like the MAGIC Foundation.
These condition-specific charts are based on longitudinal data from hundreds of individuals with RSS, such as the data from the Wollmann et al. study. This research provides the statistical basis needed to construct the curved percentile lines that accurately represent the growth distribution within the RSS population.
Growth Trajectory and Management
Early childhood is marked by slow gains in height and weight, and many children also exhibit a poor appetite. As they get older, their bone age, which is often delayed in early years, can accelerate rapidly around the ages of 8 or 9. This acceleration means they may enter puberty earlier than their peers, which can limit the total time available for growth. Without intervention, the final adult height for individuals with RSS is significantly below the average, with studies reporting average heights of approximately 151 cm for males and 140 cm for females.
To address these growth challenges, growth hormone (GH) therapy is a common and often effective treatment. Studies have demonstrated that GH therapy can significantly improve growth velocity during childhood and increase final adult height by an average of 7-9 cm in children with RSS. The effectiveness of this treatment is monitored directly on the RSS-specific growth charts. The goal is to see the child’s growth curve move upward, ideally crossing into higher percentile lines on the RSS chart, which indicates a positive response to the therapy.
Effective management also requires careful attention to nutrition. Simply overfeeding a child with RSS does not necessarily lead to greater height; instead, it can result in the child becoming overweight without a corresponding gain in stature. The focus is on providing well-balanced nutrition to support the growth potential spurred by medical treatments like GH therapy.
Monitoring Beyond Height and Weight
Comprehensive care for a child with Russell-Silver Syndrome extends beyond tracking their stature. A feature of the syndrome is body asymmetry, where one side of the body grows more slowly than the other. This is often most noticeable in the limbs, leading to a leg length discrepancy, but it can affect any part of the body. Clinicians monitor this by taking precise measurements of limb lengths and circumferences to quantify the degree of asymmetry and determine if interventions, such as a shoe lift, are needed.
Another important metric tracked on the RSS-specific chart is head circumference. Children with RSS characteristically have a head size that is normal, but because their body is small, their head appears disproportionately large. This is referred to as relative macrocephaly. The RSS-specific chart places this finding in the correct context, showing that the head circumference is typical when compared to other children with the same syndrome.