Metacarpophalangeal pattern profile analysis in Noonan syndrome

Abstract

Metacarpophalangeal pattern (MCPP) analysis is an application of an anthropometric technique that provides a quantitative assessment of the amount and direction of abnormality in the hand skeleton. MCPP analysis was undertaken on 15 individuals (9 males, 6 females) with Noonan syndrome ranging in age from 0.1 to 36 years with a mean age at 11.6 years. The overall average Z score for the MCPP variables was -2.1 and the range was -2.5 (for metacarpal two) and -1.5 (for middle phalanx 5). The average hand pattern variability index, a measure of hand bone length relationships, was abnormal. A Pearsonian correlation analysis was used to assess similarity between the mean pattern and each of the 15 individual patterns. Nine (60%) of the fifteen individuals with Noonan syndrome had significant positive correlations (P < 0.05), indicating homogeneity or similarity in the hand patterns. A stepwise discriminant analysis was performed on Z score data from the individual hand bone measurements on the 15 subjects with Noonan syndrome and 41 healthy controls (24 females, 17 males; mean age = 13.1 years with age range of 9.6 to 18 years). This analysis produced a discriminant function with two MCPP variables (metacarpal 1 and middle phalanx 3) entering into the function and producing a correct classification rate of 93%. The two MCPP variables contributed to the overall difference between individuals with Noonan syndrome and the normative sample. The hand pattern variability index was outside of the normal range, indicating an abnormal MCPP with multivariate analysis. The MCPP analysis may be useful as a tool for diagnosis in screening subjects for Noonan syndrome.

Fig. 1.

A typical hand radiograph from an 11-year-old male with Noonan syndrome.

Fig. 2.

Mean MCPP on 15 individuals with Noonan syndrome. Star indicates the bone that was selected in the discriminant analysis.

Fig. 3.

Histogram depicting normal and Noonan syndrome classification by discriminant analysis. D = 0.69 + 0.49 (Z score of metacarpal 1) + 0.63 (Z score of middle phalanx 3).