Growth Standards for Children With Smith-Magenis Syndrome (SMS).

Area of Science:

• Genetics and Developmental Biology
• Pediatric Endocrinology
• Clinical Genetics

Background:

• Smith-Magenis syndrome (SMS) is a complex genetic disorder caused by RAI1 gene haploinsufficiency, characterized by distinct facial features, neurobehavioral differences, and growth abnormalities.
• Existing growth references are inadequate for monitoring individuals with SMS, hindering accurate clinical assessment and research.
• Short stature and central obesity are common in SMS, necessitating specific growth parameters.

Purpose of the Study:

• To develop the first standardized growth curves for individuals with Smith-Magenis syndrome.
• To provide clinicians with reliable tools for monitoring linear growth, weight gain, and head circumference in SMS patients.
• To establish reference data for growth assessment in both clinical care and research settings for SMS.

Main Methods:

• Anthropometric data (length/height, weight, head circumference) were collected from 190 SMS patients (birth to adulthood) through direct encounters, parental reports, and medical records.
• Sex-specific length/height-for-age and weight-for-age curves (0-15 years) were created using polynomial smooth splines.
• Head circumference-for-age curves (0-5 years) were generated by pooling data from both sexes.

Main Results:

• The study generated the first standardized length/height-for-age, weight-for-age, and head circumference-for-age curves specifically for individuals with SMS.
• These curves include 5th, 50th, and 95th percentile lines, covering ages from birth through 15 years for height and weight, and birth through 5 years for head circumference.
• The data encompass nearly 6000 measurements, providing a robust dataset for growth assessment.

Conclusions:

• The newly developed growth curves are essential for monitoring and managing growth parameters in individuals with Smith-Magenis syndrome.
• These standardized charts will facilitate consistent clinical care and improve the accuracy of research studies involving SMS.
• The availability of these curves allows for better expectation setting regarding growth trajectories in the SMS population.