We examined the utility of incorporating a PGSheight in the evaluation of pediatric patients with short stature. Children with ISS had a comparable PGS-predicted height as children with familial (genetic) short stature. The primary diagnostic difference between these groups is that children with familial short stature manifest heights in line with those of their parents, while children with ISS do not. To further explore this difference, we directly compared height predictions based on the PGSheight to those based on mid-parental height. Using mid-parental height, children with ISS were predicted to have heights near the population mean, but using the PGSheight, children were predicted to be significantly below the mean. To test the clinical implications of this discordance, we examined whether the PGSheight could distinguish between children diagnosed with ISS and pathologic short stature. The PGSheight was able to modestly discriminate the two groups, while mid-parental height could not. These findings suggest that mid-parental height estimates may miss genetic factors captured by the PGSheight, thereby leading to a misclassified ISS diagnosis. Incorporating polygenic height predictors could improve diagnostic accuracy, ultimately improving clinical outcomes for children with ISS.
Studies in prospective, population-based cohorts have shown that polygenic scores for height can improve adult height predictions and identify children at risk for short stature in adulthood.11,12 Our study extends this work to children with short stature who are undergoing a diagnostic evaluation seeking an explanation for their height. Short stature comprises a heterogeneous collection of diagnoses, ranging from benign conditions such as familial short stature to underlying diseases. Consequently, diagnostic evaluations can be extensive, but leave many children without an explanation.9,22,23
An adult height estimate based on parental heights (MPH) is typically used to estimate a child’s genetically determined adult height potential. This study highlights the potential limitations of MPH and suggests that it may not accurately measure polygenic drivers of growth for all children presenting for evaluation. This discordance may be particularly apparent among children referred for an endocrine evaluation as one indication for referral is discordance between the child’s height and their MPH. Consistently, children with ISS in this cohort had average parental heights, so short stature was not expected by the clinician based on mid-parental height alone.
The inherent uncertainty of an ISS diagnosis can often lead to prolonged monitoring for latent disease that has not revealed itself.24 In this study, we show that the PGSheight, but not the MPH, improved discrimination of children with underlying disease from those children that remain with ISS even after a specialist’s evaluation. While significant, the magnitude of the improvements were relatively modest. The most likely explanation for the modest improvement is that ISS represents a heterogeneous collection of etiologies including rare genetic variation or sub-clinical disease.25 An unmeasured polygenic predisposition could be considered an additional, testable cause of short stature in this population. A polygenic approach to height estimation could provide some children with ISS an explanation for their short stature, allowing for appropriate de-escalation of care for disease monitoring.
Discordance between parental and polygenic height prediction could have many explanations including misestimation of parental heights due to inaccurate reporting or misattributed paternity.26 In one study, inaccurate self-reporting of parental heights was common, with 30% of couples having a self-reported MPH that was more than 2 centimeters different than measured MPH.27,28 In these instances, the PGSheight could be a valuable addition to a diagnostic algorithm, in particular for those children diagnosed with ISS. Another application would be for adopted children with unknown parental heights, for whom MPH estimates are not available.
Recessive genetic variation or de novo genetic mutations are well recognized but often underdiagnosed causes of ISS. A recent meta-analysis has shown that exome sequencing and chromosomal microarray can identify a genetic etiology in 27.1% and 13.6% of patients, respectively, that were previously diagnosed with ISS.25 In children with ISS, the PGSheight in conjunction with MPH could identify children in whom additive genetic variation is unlikely to be an explanation and who are more likely to carry rare and potentially clinically actionable variants. This approach could improve the yield of clinical sequencing studies for children with ISS.29
This study's strengths include the use of expert-adjudicated real-world diagnosis labels and a polygenic score derived from the largest genome-wide association study to date. There are also limitations. These data are from a tertiary medical center and represent a highly selected population that may differ from typical pediatric populations. Additionally, the PGSheight was derived from a European ancestry population, limiting its applicability across different genetic ancestries.12 We were unable to assess associations among children of non-European ancestries as there were fewer than 10 total cases of ISS in children of African, Asian, and Hispanic ancestries. Future research should aim to validate these findings in more diverse populations to enhance the generalizability of PGSheight across different genetic ancestries. Additionally, prospective studies could assess the real-world impact of incorporating PGSheight into diagnostic algorithms for short stature.
In summary, we show that the PGSheight measures a polygenic predisposition to shorter height not fully captured by MPH and can modestly discriminate children with ISS from those with short stature due to pathology. Incorporating the PGSheight into clinical practice not only could provide reassurance to children, parents, and clinicians by helping to identify the etiology of ISS, but also facilitates more targeted and efficient care, potentially allowing for the de-escalation of unnecessary diagnostic procedures.