Introduction

Definition of femoral-facial syndrome

Femoral Facial syndrome (FFS), also known as femoral hypoplasia, is a rare disorder that is sporadic, meaning it happens randomly in a population. It causes a baby to be born with underdeveloped thigh bones, the femur, and abnormal facial features.¹

Etiology and pathogenesis

The exact cause of FFS is still not known, and most cases are known to happen randomly. However, it was found that genetics and environmental influences can play a role.¹

Genetic factors

In some patients, it was reported that a genetic change at the end of the long arm (q) in chromosome 2, more specifically 2q37.2 promotes the development of FFS. 

There are also reports of affected people within the same family, suggesting an autosomal dominant inheritance, meaning the gene variant can be inherited from either parent, and the risk of passing from the affected parent to their child is at 50%.^2,3

Environmental influences

In most cases, it has been shown a link to gestational diabetes has been shown. This has been the cause of the structural abnormalities in the newborns.³ 

Epidemiology^3,4

Prevalence and incidence

FFS is a very rare disorder that appears to affect more males than females, with fewer than 100 cases worldwide. 

Clinical presentation^1,5

Symptoms that are most frequent (80-99%):

• Absence or abnormal growth of the femur
• Cleft palate
• Retracted jaw or a small jaw
• Shorter limbs
• Abnormal size of the vertebrae

Signs that are relatively frequent (20-30%):

• Thin lips and a longer philtrum
• Slanted eyelids
• Low-set ears or an absence of ears
• Fused bones or spine
• Hip dysplasia
• Deformed foot
• Extra toes
• Maternal diabetes

Signs that are less frequent (5-29%):

• Cross-eyed eyes
• Fusion in the ribs
• Scoliosis
• Underdeveloped kidneys
• Abnormal kidney function
• Enlarged heart ventricles 
• Enlarged penis

Diagnostic criteria^1,4,5,6

Physical examination

. One of the key features for diagnosing an individual with FFS is the underdeveloped femur bone. For the doctors to diagnose a child with FFS, there should be the presence of at least two of the following signs and symptoms:

• Longer, more spaced-out philtrum
• Underdeveloped lower jaw and mouth
• Thin upper lips
• Upward slanting of the eyelids

Imaging techniques

Some of the techniques that are used to help with the diagnosis of FFS include:

• Radiography
• MRI scanning
• CT scanning
• Genetic testing - this may help to figure out the cause of FFS, i.e. if it is genetic or not. 

Differential diagnosis^1,5,6

These diseases include:

• Camptomelic syndrome - a rare congenital skeletal disorder of autosomal recessive inheritance. It is characterised by a short stature with an angular shape of the femur bone, an abnormal pelvic and shoulder area. Other symptoms include, flat face with wide-spaced eyes and a small jaw
• Caudal regression syndrome - also a rare disorder that causes the abnormal development of the tailbone in a foetus, where there could also be an absence of the tailbone

Symptomatology^1,2

In most cases, any individual with FFS will have experienced complications caused by the symptoms of FFS, including:

• Musculoskeletal symptoms - mobility and motor issues, orthopaedic complications
• Craniofacial symptoms - feeding issues and respiratory difficulties
• Other complications - developmental delays and growth retardation

Management and treatment

Your doctor may opt for a multidisciplinary approach, which would include the intervention of surgery to help alleviate some of the more serious bone abnormalities that are associated with FFS.

The treatment can include the coordination of different specialists, from paediatricians, surgeons, dental specialists, speech specialists and other doctors who specialise in different areas of the body and will plan the treatment and the rehabilitation of your child. Surgery may be required to treat the cleft palate.^1,6

Conclusion

FFS is a very rare, sporadic syndrome that causes your child to have absent or underdeveloped femur bones and other craniofacial abnormalities. Since the exact cause and pathophysiology of FFS are still unknown, researchers suspect maternal diabetes and genetic factors to be the cause. However, more research is required to fully understand the cause, to better help in the treatment and management of FFS.