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Updated: Jan 16, 2026
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
The Head Circumference Height Index (HCH-I) to Quantify Relative Macrocephaly and Aid Identification of
Moira S Cheung1,2, Ruggero Lanzafame1, Karen J Low3,4
1Great Ormond Street Hospital NHS Foundation Trust, Department of Paediatric Endocrinology, London, UK.
Insights
A new Head Circumference Height Index (HCH-I) helps identify hypochondroplasia (HCH), a rare skeletal disorder. This simple index, measuring head-to-height disproportion, aids pediatricians in diagnosing HCH and other genetic conditions.
Area of Science:
- Genetics and Human Diseases
- Pediatrics and Child Health
- Medical Diagnostics
Background:
- Hypochondroplasia (HCH) is a rare skeletal dysplasia linked to FGFR3 gene variants.
- Distinct head-to-height proportions may aid in HCH diagnosis.
- Existing diagnostic methods may benefit from supplementary tools.
Purpose of the Study:
- To develop and validate a simple index for head-stature disproportion to assist in HCH diagnosis.
- To assess the diagnostic utility of the Head Circumference Height Index (HCH-I) in identifying HCH.
- To provide a practical tool for pediatricians in identifying potential cases of HCH.
Main Methods:
- Defined the Head Circumference Height Index (HCH-I) as height Z-score - 1/2 head circumference Z-score using UK90 growth references.
- Validated the HCH-I using data from 364 children with HCH and 4620 children from the Cambridge Infant Growth Study (CIGS).
- Determined a cut-off of -2 for HCH-I to indicate significant head-height disproportion.
Main Results:
- The mean HCH-I was -3.0 (SD 1.2) in the HCH cohort versus -0.2 (SD 0.9) in the CIGS cohort.
- An HCH-I below -2 correctly identified 78% of children with HCH.
- Only 2.4% of CIGS children had an HCH-I below -2, indicating high specificity.
Conclusions:
- The HCH-I is a simple, statistically-based index for quantifying head-height disproportion.
- An HCH-I below -2 effectively identifies children with disproportionate head-to-height ratios, suggesting HCH or other genetic disorders.
- The HCH-I offers a practical and useful tool for clinical settings to aid in the early identification of HCH.
Abstract:
Hypochondroplasia (HCH) is a rare skeletal dysplasia caused by pathogenic variants in the FGFR3 gene. We hypothesized that the relative disproportion between head circumference and height in HCH might be diagnostically informative and generated a simple index of head-stature disproportion to help pediatricians diagnose HCH. The Head Circumference Height Index (HCH-I), based on formal statistical principles, is defined as height Z-score - 1/2 head circumference Z-score, with the Z-scores based here on the UK90 growth reference. An HCH-I below the cut-off of -2 indicates substantial head-height disproportion. We validated the index by comparing children diagnosed with HCH (n = 364), using data from the recent European HCH growth charts, to children from the Cambridge Infant Growth Study (CIGS) (n = 4620). The mean (SD) HCH-I was -3.0 (1.2) in the HCH cohort, compared to -0.2 (0.9) in the CIGS cohort. An HCH-I below -2 correctly identified 78% of children with HCH, while only 2.4% of CIGS children fell below the cut-off. An HCH-I below -2 identifies children with head-height disproportion who may have HCH or another genetic disorder. The index is deliberately simple to calculate and should prove useful in clinical practice.
