Brachydactyly type C

Alternate names

BDC; Brachydactyly Haws type

Definition

Brachydactyly type C is a very rare congenital condition that is characterized by shortening of certain bones in the index, middle and little fingers. The bones of the ring finger are typically normal.

Epidemiology

This type of brachydactyly is rare with only few reported pedigrees.

Cause

Brachydactyly type C is typically caused by changes (mutations) in the GDF5 gene.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

Inheritance of both types is autosomal dominant.

Signs and symptoms

• It that is characterized by shortening of certain bones in the index, middle and little fingers.
• The bones of the ring finger are typically normal.
• Other abnormalities may also be present such as hypersegmentation (extra bones) of the index and middle fingers; ulnar deviation (angled towards the fifth finger) of the index finger; and unusually-shaped bones and/or epiphysis (end of a long bone).

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Aplasia/Hypoplasia of the 1st metacarpal(Absent/small 1st long bone of hand)
• Cone-shaped epiphyses of the middle phalanges of the hand(Cone-shaped end part of the middle hand bones)
• Pseudoepiphyses of the 2nd finger
• Pseudoepiphyses of the 3rd finger
• Short 2nd finger(Short index finger)
• Short 3rd finger(Short middle finger)
• Short middle phalanx of finger(Short middle bone of finger)
• Type C brachydactyly
• Ulnar deviation of finger(Finger bends toward pinky)

30%-79% of people have these symptoms

• Abnormal fingernail morphology(Abnormal fingernails)
• Clinodactyly of the 5th finger(Permanent curving of the pinkie finger)
• Complete duplication of distal phalanx of the thumb(Complete duplication of outermost bone of the thumb)
• Cone-shaped epiphysis(Cone-shaped end part of bone)
• Enlarged epiphysis of the middle phalanx of the 2nd finger(Enlarged end part of the middle bone of the index finger)
• Enlarged epiphysis of the middle phalanx of the 3rd finger(Enlarged end part of the middle bone of the middle finger)
• Enlarged epiphysis of the proximal phalanx of the 2nd finger(Enlarged end part of innermost long bone of index finger)
• Enlarged epiphysis of the proximal phalanx of the 3rd finger(Enlarged end part of innermost long bone of the middle finger)
• Short 1st metacarpal(Shortened 1st long bone of hand)
• Short metatarsal(Short long bone of foot)
• Short stature(Decreased body height)
• Stippling of the epiphysis of the distal phalanx of the thumb(Speckled calcifications in the end part of the outermost thumb bone)
• Triangular epiphysis of the middle phalanx of the 2nd finger(Triangular end part of the middle bone of the index finger)
• Triangular epiphysis of the middle phalanx of the 3rd finger(Triangular end part of the middle bone of the middle finger)
• Triangular epiphysis of the proximal phalanx of the 2nd finger(Triangular end part of innermost long bone of index finger)
• Triangular epiphysis of the proximal phalanx of the 3rd finger(Triangular end part of innermost long bone of the middle finger)
• Triangular shaped middle phalanx of the 2nd finger(Triangular shaped middle bone of index finger)
• Triangular shaped middle phalanx of the 3rd finger(Triangular shaped middle bone of the middle finger)
• Triangular shaped proximal phalanx of the 2nd finger(Triangular shaped innermost bone of index finger)
• Triangular shaped proximal phalanx of the 3rd finger(Triangular shaped innermost bone of middle finger)
• Ulnar deviation of the 2nd finger
• Ulnar deviation of the 3rd finger

5%-29% of people have these symptoms

• Delayed skeletal maturation(Delayed bone maturation)
• Metatarsus valgus
• Symphalangism affecting the phalanges of the hand(Fused finger bones of the hand)
• Talipes equinovalgus
• Talipes equinovarus(Club feet)

Diagnosis

Clinical evaluation of hands. X-rays of hands and pattern profile analysis. The ring finger is always the longest, longer than the index (hyperphalangism detected on radiological examination)..

Treatment

There is no specific management or treatment that is applicable to all forms of brachydactyly.. Plastic surgery is only indicated if the brachydactyly affects hand function or for cosmetic reasons, but is typically not needed. Physical therapy and ergotherapy may ameliorate hand function.

Prognosis

Prognosis for the brachydactylies is strongly dependent on the nature of the brachydactyly, and may vary from excellent to severely influencing hand function. If brachydactyly forms part of a syndromic entity, prognosis often depends on the nature of the associated anomalies.

NIH genetic and rare disease info

• NIH info on Brachydactyly type C

Brachydactyly type C is a rare disease.

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