Evaluation of qualitative methods for phenotyping brachymesophalangia-V from radiographs of children.

OBJECTIVE

Brachymesophalangia-V (BMP-V), the general term for a short and broad middle phalanx of the 5th digit, presents both alone and in a large number of complex brachydactylies and developmental disorders. Past anthropological and epidemiological studies of growth and development have examined the prevalence of BMP-V because small developmental disorders may signal more complex disruptions of skeletal growth and development. Historically, however, consensus on qualitative phenotype methodology has not been established. In large-scale, non-clinical studies such as the Fels Longitudinal Study and the Jiri Growth Study, quantitative assessment of the hand is not always the most efficient manner of screening for skeletal dysmorphologies. The current study evaluates qualitative phenotyping techniques for BMP-V used in past anthropological studies of growth and development to establish a useful and reliable screening method for large study samples.

METHODS

A total of 1,360 radiographs from Jiri Growth Study participants aged 3-18 years were evaluated. BMP-V was assessed using three methods: (1) subjective evaluation of length and width of the bone; (2) comparison with skeletal age-matched radiographs; and (3) subjective evaluation of the length of the middle 4th and 5th phalanges.

RESULTS

We found that the method that uses skeletal age-matched reference radiographs is the better tool for assessing BMP-V because it considers the shape, rather than solely the length and width of the bone, which can be difficult to judge accurately without measurement. This study highlights the complexity of phenotypic assessment of BMP-V and by extension other brachydactylies.