Despite the advances in molecular genetics, the diagnosis of most dysmorphic syndromes is still a clinical one. Even in syndromes where the molecular basis has been elucidated, clinical dysmorphology retains its value since mutation detection is still a laborious task in most genetic syndromes and precise clinical pre-selection is essential.
Dysmorphic signs are often described in a qualitative fashion such as “short nose” or “widely spaced eyes”, but the clinical impression can be misleading. The depressed nasal bridge and the epicanthic folds in patients with Down syndrome, for example, give the impression that their eyes are widely spaced, while in fact they are significantly nearer than the norm [Goodman and Gorlin, 1977]. Therefore, most dysmorphologists advocate the use of quantitative measures for dysmorphic features wherever possible [Goodman and Gorlin, 1977; Hall et al., 1989; Aase, 1990; Jones, 1997]. This approach has extensively been used in the evaluation and characterization of a number of dysmorphic syndromes [Allanson et al., 1993; Allanson and Hennekam, 1997; Allanson et al., 1997; Allanson et al., 1999; Ward et al., 2000]. As more and more patients with classic dysmorphic syndromes reach adulthood, age-related changes in facial phenotype are increasingly recognized and have been incorporated into syndrome delineation studies [Allanson et al., 1985; Allanson, 1989; Fryns, 1992; Hunter and Allanson, 1994; Allanson and Cole, 1996].
Despite this importance, measurements of normal facial dimensions have often only been carried out for a small number of individuals or in a limited age range [Feingold and Bossert, 1974; Goodman and Gorlin, 1977; Farkas, 1994]. In particular, data on anthropometric measurements in adults is sparse and incomplete. In this study, we present normal values for nose size and philtrum length based on measurements on 2,500 healthy individuals of central European origin ranging in age from zero to 97 years.
MATERIALS AND METHODS
Probands were ascertained in newborn nurseries, day care centers, schools, large companies, during military service, and in nursing homes for the elderly. All probands were of central European descent and living in Switzerland. From birth to 28 years of age, 50 persons were measured for each year of age, i.e., 50 newborns, 50 one-year-olds, 50 two-year-olds, etc. From 29 to 44 years of age, two consecutive years were grouped and 50 persons were measured for each age group. From 45 to 86 years of age, three consecutive years were grouped and 50 persons were measured for each age group. The last group contained measurements of 50 persons from 87 to 97 years of age. Thus, a total of 2,500 individuals were measured. An equal number of male and female subjects were measured in each age group.
Nose length, nasal protrusion, and philtrum length were measured as illustrated in Figure 1. All measurements were carried out by a single experienced investigator (L.E.) using a rigid transparent plastic caliper. The lower nasal tip (lnt) was defined as the lowest visible point of the nose when looking at the caliper at a 90-degree angle. The subnasale landmark (sn) is the midpoint of the angle at the columella base, where the lower border of the nasal septum and the surface of the upper lip meet [Farkas, 1994]. The pronasale point (prn) is the most protruded point of the apex nasi, identified in lateral view of the rest position of the head[Farkas, 1994]. The sellion (se) is the deepest landmark located on the bottom of the nasofrontal angle [Farkas, 1994]. The labiale superius landmark (ls) is the midpoint of the upper vermilion line [Farkas, 1994]. Nose length was defined as the distance from the sellion landmark to the lower nasal tip. Nasal protusion was defined as the distance from the subnasale landmark to the pronasale point. Philtrum length was defined as the distance from the subnasale landmark to the labiale superius landmark.
The data was analyzed using the statistical package Statview 5.0 (SAS Institute, Inc., Cary Measurements, Cary, NC) for male and female subjects were studied separately. Skewness (measure of a distribution's symmetry) and kurtosis (measure of a distribution's “peakedness”) were calculated for each age group. No major deviations from a normal distribution were observed. Mean and SD were calculated for each age group and the values for Mean, Mean +2SD, Mean +1SD, Mean −1SD and Mean −2SD were plotted against age. The resulting scattergram was smoothed using the lowess smoothing algorithm provided by Statview. Different tension parameters were tried for the lowess algorithm to ensure that the smoothed curves represent the original data reasonably well. For details how lowess is computed, see Cleveland .
Growth curves for nose length, nasal protrusion, and philtrum length for both sexes are given in Figure 2. A pediatric growth curve with normal values from zero to 20 years that is more suitable in a clinical setting is available from the authors on request. Unisex growth curves, combining the measurements for males and females in a single curve, are also available on request. Though slightly less accurate than sex-specific growth curves, unisex growth curves might be easier to handle in a clinical setting.
We have established growth curves for nose length, nasal protrusion, and philtrum length based on measurements in 2,500 normal individuals. This data sample is larger than the data samples obtained by other authors [Feingold and Bossert, 1974; Goodman and Gorlin, 1977; Farkas, 1994] and covers the largest age range. As expected, nose length, nasal protrusion, and philtrum length tend to be larger in males than in females. The curves for nose length illustrate that the nose continues to grow throughout life and thus support the frequent (subjective) observation that old people often have large noses. While all bony structures of the head and body eventually reach their definite length in early adulthood, the nose and ears are mainly formed from cartilage, which continues to grow throughout life. This relation is less pronounced for nasal protrusion. The curves for philtrum length have a very characteristic shape with a first peak in adolescence, followed by an actual decline of philtrum length in early adulthood, and a regain of philtrum length after the age of 30. As this unusual growth pattern occurs roughly around puberty (first peak of philtrum length at approximately 18 years in males and 12 years in females), the S-shaped curve might reflect the major facial remodeling that takes place during that period.
Since we have limited our data to measurements from individuals of central European origin, the obtained growth charts are not applicable to patients of African or Asian decent. Hopefully, our work will inspire others to complement this data with measurements in other ethnic groups.
This study was initiated during a fellowship of one of the authors (A.S.) with the unforgettable David W. Smith. It is to him that we dedicate this paper.