What are the other Names for this Condition? (Also known as/Synonyms)

• FMD (Frontometaphyseal Dysplasia)

What is Frontometaphyseal Dysplasia? (Definition/Background Information)

• Frontometaphyseal Dysplasia (FMD) is a genetic disorder characterized by abnormalities in skeletal development and problems in other organs of the body
• It is part of a group of diseases called otopalatodigital spectrum disorders, which also includes otopalatodigital syndrome type 1, otopalatodigital syndrome type 2, and Melnick-Needles syndrome
• In general, these disorders involve hearing loss (due tomalformations in the tiny bones in the ears, called ossicles), cleft roof of the mouth (palate), and defects of the bones in the fingers and/or toes (digits)
• Frontometaphyseal Dysplasia is distinguished from the other disorders of the group by the presence of joint deformities (contractures) that restrict the movement of certain joints
• Other symptoms may include prominent brow ridges; wide-set and downward-slanting eyes; a very small lower jaw and chin (micrognathia); small, missing or misaligned teeth; bowed limbs; an abnormal curvature of the spine (scoliosis); obstruction of ureters; heart defects; and breathing problems. Males generally have more severe features than females
• It is caused by mutations in the FLNA gene. Inheritance is X-linked
• Treatment of Frontometaphyseal Dysplasia depends on the problems present and may include hearing aid and surgery to correct the facial findings and the bone defects

(Source: Frontometaphyseal Dysplasia; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Frontometaphyseal Dysplasia? (Age and Sex Distribution)

• Frontometaphyseal Dysplasia is a rare congenital disorder. The presentation of symptoms may occur at birth
• Both males and females may be affected, although the symptoms are more significant in males than females
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Frontometaphyseal Dysplasia? (Predisposing Factors)

• A positive family history may be an important risk factor, since Frontometaphyseal Dysplasia is an inherited condition
• Currently, no other risk factors have been clearly identified for FMD

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Frontometaphyseal Dysplasia? (Etiology)

• Inheritance is X-linked. This means that if a parent of a patient with Frontometaphyseal Dysplasia has the FLNA gene mutation, the chance of transmitting the mutation in each pregnancy is 50%
• When the mother has an FLNA mutation, males who inherit the mutation will be affected; females who inherit the mutation may have some features
• Males with FMD transmit the disease-causing mutation to all of their daughters and none of their sons

(Source: Frontometaphyseal Dysplasia; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

What are the Signs and Symptoms of Frontometaphyseal Dysplasia?

In general, males tend to be more severely affected than females. Females may present with the characteristic craniofacial features and scoliosis. The main symptoms of Frontometaphyseal Dysplasia in males include:

• Skeletal dysplasia (enlargement of the bones in the frontal part of the skull, skull base sclerosis, as well as in the medial part (diaphysis) of the long bones and the part between the diaphysis and the end parts of the bones, small tips of the bones of the fingers)
• Progressive contractures of the hand and other bones of the body over the first 20 years resulting in limited movement of the hand, fingers, wrists, elbows, knees, and ankles
• Scoliosis
• Limb bowing
• Deformed fingers
• Facial dysmorphism (big frontal, wide-spaced eyes, down-slanting eye slits, broad nose bridge and tip, small or less teeth than normal and occasionally craniosynostosis (when the sutures of the skull closed too early))
• Hearing loss.

Other features include congenital heart malformation, congenital subglottic stenosis (narrowing of the airways), a slender body, with underdeveloped muscles around the shoulders and in the inside of the hands. Males with Frontometaphyseal Dysplasia can present with obstruction of the ducts connecting the ureters with bladder and enlarged kidneys (hydronephrosis). Intelligence is normal.

The signs and symptoms of Frontometaphyseal Dysplasia may include:

• Ankle contracture
• Antegonial notching of mandible
• Anteriorly placed odontoid process
• Arachnodactyly
• Broad phalanges of the hand
• Coarse facial features
• Coat hanger sign of ribs
• Cor pulmonale  
• Coxa valga
• Delayed eruption of teeth
• Dental malocclusion
• Elbow flexion contracture
• Genu valgum
• Hirsutism
• Hydroureter
• Increased density of long bone diaphyses
• Intellectual disability
• Knee flexion contracture
• Large foramen magnum
• Long foot
• Long phalanx of finger
• Mitral valve prolapse
• Partial fusion of carpals
• Partial fusion of tarsals
• Persistence of primary teeth
• Pointed chin
• Scapular winging
• Selective tooth agenesis
• Short chin
• Skeletal muscle atrophy
• Stridor
• Wide nasal bridge
• Wrist flexion contracture

Based on the frequency of symptoms observed, the following information may be noted:

Very frequently present symptoms in 80-99% of the cases:

• Abnormality of dental morphology
• Abnormality of the metaphysis
• Absent/hypoplastic paranasal sinuses
• Bowing of the long bones
• Camptodactyly of finger
• Conductive hearing impairment
• Craniofacial hyperostosis
• Downslanted palpebral fissures
• Hypertelorism
• Joint stiffness
• Micrognathia
• Prominent supraorbital ridges
• Reduced number of teeth
• Sensorineural hearing impairment

Frequently present symptoms in 30-79% of the cases:

• Abnormal form of the vertebral bodies 
• Accelerated skeletal maturation 
• Elbow dislocation 
• Fused cervical vertebrae 
• High palate
• Hypoplasia of the musculature 
• Irregular metacarpals 
• Long fingers 
• Long metacarpals
• Posterior vertebral hypoplasia    
• Scoliosis 
• Short distal phalanx of hallux 
• Short distal phalanx of the thumb 
• Synostosis of carpal bones 
• Ulnar deviation of finger

Occasionally present symptoms in 5-29% of the cases:

• Atrioventricular canal defect 
• Hydronephrosis 
• Subglottic stenosis 
• Tracheal stenosis
• Ureteral stenosis 
• Urethral stenosis

(Source: Frontometaphyseal Dysplasia; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Frontometaphyseal Dysplasia Diagnosed?

Frontometaphyseal Dysplasia is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Frontometaphyseal Dysplasia?

The complications of Frontometaphyseal Dysplasia may include:

• Immobility of joints
• Heat abnormalities
• Physical deformities

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Frontometaphyseal Dysplasia Treated?

The treatment of Frontometaphyseal Dysplasia depends on the symptoms present in the person, and may include:

• Hearing loss aids for deafness
• Surgery to correct the facial deformities including the frontal deformity
• Surgery to correct the joint contractures, the limb bowing, and the scoliosis

(Source: Frontometaphyseal Dysplasia; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Frontometaphyseal Dysplasia be Prevented?

Currently, Frontometaphyseal Dysplasia may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Frontometaphyseal Dysplasia? (Outcomes/Resolutions)

• The prognosis of Frontometaphyseal Dysplasia is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Frontometaphyseal Dysplasia:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/