An anthropometric study was undertaken to assess head proportions of patients with X-linked hypophosphatemia (XLH). Fourteen morphometric parameters of the head were measured and 10 cephalic indices calculated in 82 affected persons (57 females and 25 males) from 55 unrelated families with XLH, and compared with the results obtained in the group of their healthy relatives (37 females and 33 males), as well as with general population control values. Normalized values (SD, z-score) were analyzed statistically. The group of healthy relatives, both males and females, differed significantly from Polish population control values in most of the normalized variables measured, making population control values useless as a control group for the analyzed XLH group. Intrafamilial values of cephalic parameters in healthy relatives of the XLH patients were finally applied for statistical analysis. Generally patients with XLH showed highly statistically significant increase in head length (males 0.95 +/- 1.07 vs. -0.37 +/- 1.02, females 0.57 +/- 1.59 vs. -0.06 +/- 1.15), significant decrease in occipital breadth (males -0.56 +/- 1.27 vs. 0.70 +/- 1.28, females -0.59 +/- 1.7 vs. 0.13 +/- 1.1) and several milder anomalies of craniofacial proportions. Mean cephalic index was significantly lower in XLH patients when compared with the healthy relatives (males -0.909 vs. 0.278 P < 0.0001, females -0.705 vs. 0.381 P = 0.007). The cephalic changes were found both in XLH children and XLH adults and were more pronounced in affected males than in females. There were no differences between offspring born by hypophosphatemic and normophosphatemic mothers.

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Dept. o f P e d i a t r i c s , Univ. Vienna and Ludwig Boltzmann The Middlesex H o s p i t a l , London, W1. UNITED KINGDOM