Brachydactyly is a medical term describing the shortening of fingers and toes due to unusually short bones. It is a congenital condition, meaning individuals are born with them. Brachydactyly Type E (BDE) is a specific form characterized by the shortening of bones in the hands and feet, specifically the metacarpals and metatarsals.
Physical Characteristics of Brachydactyly Type E
Brachydactyly Type E primarily affects the long bones of the hands (metacarpals) and feet (metatarsals). Unlike some other forms, BDE typically does not affect the phalanges, the smaller bones of the fingers and toes. This shortening of the metacarpals and metatarsals often results in hands or feet that appear smaller overall.
The fourth and fifth metacarpals and metatarsals are most frequently affected, leading to shorter fourth and fifth fingers or toes. In some instances, the first metacarpal (thumb) and first metatarsal (big toe) can also be shortened. The condition can manifest unilaterally, affecting one hand or foot, or bilaterally. Individuals with BDE may also exhibit hyperextensibility, meaning very flexible joints, particularly in the hands.
Genetic Causes and Inheritance Patterns
Isolated Brachydactyly Type E is an inherited condition. It follows an autosomal dominant inheritance pattern, meaning a person needs to inherit only one copy of the altered gene from a single parent to develop the condition. If one parent has the gene, each child has a 50% chance of inheriting BDE.
Mutations in certain genes are associated with isolated BDE, with the HOXD13 gene a primary factor. This gene regulates the development of hands and feet during embryonic growth. Alterations in the PTHLH gene have also been linked to BDE, sometimes accompanied by short stature.
Associated Syndromes and Conditions
While Brachydactyly Type E can occur as an isolated trait, meaning it is the only health issue, it frequently appears as a symptom of broader genetic syndromes. Distinguishing between isolated BDE and syndromic BDE is important for diagnosis and management.
BDE is associated with Pseudohypoparathyroidism (PHP), a hereditary disorder characterized by the body’s inadequate response to parathyroid hormone. BDE is observed in a significant percentage of PHP patients, ranging from 70% to 78%. The physical features of PHP, including BDE, short stature, a round face, and obesity, are collectively referred to as Albright’s Hereditary Osteodystrophy (AHO).
Another condition associated with BDE is Turner Syndrome, a chromosomal disorder affecting females. The presence of BDE can sometimes prompt further investigation to determine if an underlying systemic condition, such as PHP, AHO, or Turner Syndrome, might be present. This helps healthcare providers understand the full scope of an individual’s health and plan appropriate care.
Diagnosis and Management Approaches
Diagnosing Brachydactyly Type E typically begins with a physical examination, where a doctor can observe the characteristic shortening of the metacarpals and metatarsals. Confirmation of the condition often involves radiographic imaging, such as X-rays, which provide clear images of the bones and can precisely identify which ones are shortened. In mild cases, X-rays may be the only way to confirm the condition.
For most individuals with isolated BDE, medical treatment is generally not necessary. Hand and foot function is usually not significantly impaired, and the condition rarely affects overall health. However, if functional difficulties arise, such as problems with grip or walking, physical therapy can be beneficial to improve range of motion and strength.
Surgical options, such as bone lengthening procedures, are available but are typically considered elective. These procedures are usually pursued for either significant functional improvement or cosmetic reasons. It is reassuring to note that Brachydactyly Type E is not a progressive condition, meaning it does not worsen over time, nor is it considered life-threatening.