Growth, Face, and Skin Features in FILS

FILS syndrome affects the way various parts of the body grow and develop. Because the POLE gene is involved in the way almost every cell in the body copies its DNA, the physical manifestations can be seen in the face, the skin, the teeth, and the child’s overall height ^[1][2].

Distinctive Facial and Dental Features

Many children with FILS share a recognizable pattern of facial features. These are often subtle but consistent across reported cases ^[3]. You may notice some of the following:

• Prominent forehead: The forehead may appear larger or more forward-leaning than usual ^[3].
• Low hairline: The hair may start lower on the forehead and at the back of the neck than in other children ^[3].
• Eyes and Ears: The eyes may have short down-slanting palpebral fissures (the opening between the eyelids is shorter and tilts downward), and the ears may be low-set (positioned lower on the head than typical) ^[3].
• Nose and Mouth: The nose often has a long tip and columella (the tissue separating the nostrils), while the mouth may appear small ^[3].

Dental irregularities are also common ^[3]. This can include teeth that are irregular in shape or poorly aligned. While specific dental diagnoses like missing teeth (hypodontia) are not consistently reported for every child, the general “irregularity” of the teeth is a key part of the diagnosis that often requires specialized dental care ^[3].

Growth and Short Stature

One of the defining characteristics of FILS is short stature, meaning the child is significantly shorter than other children of the same age and sex ^[2][3].

This growth delay can sometimes begin even before birth, a condition known as intrauterine growth restriction (IUGR) ^[2]. While not every child with FILS is born small, many have a lower-than-average birth weight and length for their gestational age. After birth, children typically continue to grow at a slower rate than their peers ^[4].

In some cases, children with POLE mutations may also have metaphyseal dysplasia, which refers to differences in how the ends of the long bones develop ^[2]. This can further impact growth and may be evaluated by your doctor using X-rays when clinically indicated.

Dermatologic (Skin) Findings

The skin changes in FILS are notable indicators of the condition, though they alone cannot diagnose FILS. There are two primary patterns:

1. Livedo: This is a lacy, reddish-blue pattern that looks like a net beneath the skin ^[5]. In FILS, this pattern is most frequently seen on the inner sides of the upper arms and on the thighs ^[3].
2. Poikiloderma: Some children also develop poikiloderma ^[5]. This is a more complex skin change that includes three features:
   • Atrophy: Thinning of the skin.
   • Telangiectasia: Tiny, visible “spider veins” or broken blood vessels.
   • Pigment changes: Areas where the skin is darker (hyperpigmentation) or lighter (hypopigmentation) than the surrounding skin ^[6].

While the precise mechanism in FILS is not fully understood, these expected patterns are generally not painful. However, you should seek clinical assessment for any new, painful, ulcerated, rapidly spreading, or temperature-independent skin changes, as the expected FILS pattern does not automatically explain every rash or circulation symptom ^[5][3].