Facial Dysmorphology

In this section, drawings are used to depict terminology and to illustrate certain aspects of facial variation.

Many features of the face that are considered abnormal are continuous, quantitative traits, plotting above or below 2 S.D. from the mean. A continuous trait, like ear size, is quite different from a discontinuous trait such as a pre-auricular ear pit since an ear pit is considered either present or absent (figure below).

dysmorpho-traits-horiz — This illustration demonstrates the fundamental difference between continuous and discontinuous traits in human physical characteristics, using ear features as examples relevant to clinical dysmorphology. The top graph shows a continuous trait — ear size — displayed as a classic bell-shaped normal distribution curve, illustrating that ear size varies gradually and smoothly across the population, with most people clustering around an average of approximately 3.0 cm and fewer people at the extremes of very small or very large, meaning there is no clear cutoff between “normal” and “abnormal” — just a spectrum. The bottom graph shows a discontinuous trait — ear pits (small preauricular pits or dimples near the ear), displayed as a simple bar chart showing that the vast majority of people do not have ear pits at all, while a small distinct minority do, with no intermediate forms — you either have them or you don’t.

Thus, there is usually no disagreement among physicians as to whether an ear pit is present or not. However, disagreement can occur when one judges continuous traits based on impression alone, without the benefit of measurement. Nevertheless, visual appraisal alone is often the practical reality in a busy clinic. Facial measurements can be made of certain facial regions (as noted below for an example using A for outer canthal distance), and when indicated, can be measured and plotted on growth charts.

smith-face-with-graph — This illustration, adapted from Smith’s Recognizable Patterns of Human Malformation (5th Edition, edited by K.L. Jones), combines two complementary clinical tools used in dysmorphology for precise measurement of facial features. The left side shows a growth chart (graph A) with age on the x-axis (from months to years) and facial measurements on the y-axis, displaying multiple percentile curves that allow clinicians to plot and compare a patient’s facial measurements against age-normalized population norms — essential for determining whether a measurement is truly abnormal for a given age. The right side shows a facial diagram illustrating the specific standardized measurements that correspond to the growth chart, with labeled dimensions including A — inner canthal distance (between the inner corners of both eyes), B — interpupillary distance (between the centers of both pupils), and C — outer canthal distance (between the outer corners of both eyes), which are the three most fundamental and commonly used orbital measurements in dysmorphology practice.

In this web page, facial drawings illustrate how certain facial terms are used to describe facial variation.

Orbital Placement

Hypertelorism is defined by an increased interpupillary distance. Hypertelorism (right); normal (middle); hypotelorism (left).

hypertelorism-with-neck — This illustration demonstrates the clinical concept of orbital spacing variations by comparing three child facial diagrams side by side, specifically illustrating hypotelorism, normal spacing, and hypertelorism. The left face shows hypotelorism — abnormally close-set eyes where the distance between the inner corners of the eyes (inner canthal distance) is reduced, giving the eyes an unusually crowded appearance toward the center of the face. The center face shows normal orbital spacing with a red horizontal line marking the standard reference measurement between the inner canthi, representing the typical expected distance between the eyes for a child of this age. The right face shows hypertelorism — abnormally wide-set eyes where the distance between the inner corners is increased, giving the eyes a widely spaced appearance.

Palpebral Fissure Length

Often this length is actually measured and plotted. Short (left); normal (middle); large (right)

palpebral-fissures-composit — This illustration demonstrates the clinical concept of palpebral fissure length variations by comparing three child facial diagrams side by side, specifically illustrating short, normal, and long palpebral fissures. The left face shows short palpebral fissures — where the horizontal opening of the eye between the inner and outer corners is reduced, making the eyes appear small or narrow, a condition also known as blepharophimosis. The center face shows normal palpebral fissure length with a red rectangle highlighting the standard reference measurement of the eye opening, representing the typical expected horizontal length of the eye aperture for a child of this age. The right face shows long palpebral fissures — where the horizontal eye opening is wider than normal, giving the eyes a larger, more prominent appearance.

Palpebral Fissure Slant

This varies greatly with ethnic origin. Up (left); normal (middle); down (right)

palpebral-slant — This illustration demonstrates the clinical concept of palpebral fissure slant variations by comparing three child facial diagrams side by side, specifically illustrating upward slanting, horizontal, and downward slanting palpebral fissures. The left face shows upward slanting palpebral fissures — where the outer corner of the eye (lateral canthus) sits higher than the inner corner (medial canthus), with the red line angling upward from inner to outer corner, giving the eyes an upward tilted appearance commonly referred to as mongoloid slant. The center face shows horizontal palpebral fissures representing the normal orientation where the inner and outer corners of the eyes sit at essentially the same level, with the red line running straight across. The right face shows downward slanting palpebral fissures — where the outer corner of the eye sits lower than the inner corner, with the red line angling downward from inner to outer corner, commonly referred to as antimongoloid slant.

Epicanthal folds

Many variations exist. The boy on the left does not have folds. On the right image, the effect of the epicanthal fold extending above the inner canthus is illustrated.

Mid-face Hypoplasia

Midface hypoplasia (blue region below) is essentially the same thing as maxillary bone region hypoplasia. Maxillary retrusion is another way of thinking about mid-face hypoplasia. Depressed nasal bridge (not illustrated here) is often another component of mid-face hypoplasia.

Philtrum shape

The philtral groove can be thought of as representing the resultant folding effects of bilateral, inwardingly migrating neural crest cells that met at the midline. Smooth patterns however can also be normal variants or can be associated with genetic syndromes or caused by teratogens such as alcohol.

philtrum-multiple-side — This illustration compares two variations of the philtrum — the vertical groove between the nose and upper lip — which is an important anatomical landmark in clinical dysmorphology and genetic evaluations. The left diagram shows a normal philtrum, with clearly labeled features including the philtrum height (the vertical distance from the base of the nose to the upper lip border) and a well-defined philtral groove (the distinct central channel flanked by two raised ridges called philtral columns), giving the upper lip area its characteristic appearance with a normally full and well-shaped upper lip. The right diagram shows a smooth philtrum with a thin upper lip — where the philtral groove is replaced by a shallow, indistinct groove with poorly defined or absent philtral columns, and the upper lip is noticeably thinner than normal with a flattened vermillion border.

Ear Placement

Images A shows normal ear position. Low set ears are positioned below the horizontal line as illustrated in B. Low-set ears are often posteriorly rotated, reflecting an arrest in the normal anterior rotation that occurred during fetal ear development.

ear-face-diagram-with-bars — This illustration demonstrates the clinical method for assessing ear position and rotation on a child’s head, which are important dysmorphological measurements used in genetic evaluations. The top row (A) shows a normally positioned ear — the left diagram illustrates that the ear should be positioned in the posterior one-third of the face (measured by line A from the outer eye corner to the back of the head), and the right diagram shows that a normal ear tilt is approximately 20 degrees from vertical, meaning the ear is nearly upright. The bottom row (B) shows an abnormally positioned and rotated ear — the left diagram illustrates a low-set ear positioned below the standard landmark line A, and the right diagram shows a posteriorly rotated ear tilted at 30 degrees or more from vertical, meaning the top of the ear leans noticeably backward.

Anatomic Landmarks, Ear

ear-diagram — This illustration is a labeled anatomical diagram of the external human ear (auricle/pinna) used in clinical genetics and dysmorphology to precisely identify and describe the specific structural components of the ear during physical examination. The labeled structures include the superior helix (the uppermost curved outer rim of the ear), superior crus and inferior crus (the two branches that form the upper portion of the antihelix), antihelix (the curved inner ridge that runs parallel to and inside the helix), concha (the deep bowl-shaped hollow at the center of the ear leading to the ear canal), tragus (the small pointed projection of cartilage at the front of the ear opening), helix (the complete outer curved rim of the ear), and lobe (the soft, fleshy lower portion of the ear).

Other Anatomic Landmarks, Face

face-Infant-with-labels-dar — This illustration is a labeled anatomical diagram of an infant’s face used in clinical genetics and dysmorphology to precisely identify and describe specific facial regions and landmarks during physical examination. The labeled structures include the glabella (the smooth area between the eyebrows), supraorbital ridge (the bony prominence above the eye socket), temporal region (the side of the forehead), inner canthus (the inner corner of the eye), nasal alae (the flared outer wings of the nostrils), philtrum area (the vertical groove between the nose and upper lip), vermillion border of the lip (the distinct edge where the colored lip meets the surrounding skin), maxillary (midface) region (the central mid-face area), nasal bridge (the upper bony part of the nose), and columella (the tissue separating the two nostrils).