Familial Brachydactyly in an Indian Family : A case report

Brachydactyly or short digit is a rare deformity involving fingers and toes. We present a rare family with 6 known members affected with similar pattern of brachydactyly, affecting only bilateral index fingers. The knowledge of this entity is important and a thorough clinical and radiological evaluation is mandatory for any patient with digital deformities.


Introduction
Brachydactyly (Greek: "short digits") is a general term that refers to disproportionately short fi ngers and toes, and forms part of the group of limb malformations characterized by bone dysostosis 1 .But it has a clinical spectrum ranging from minor digital hypoplasia to complete aplasia.Among the 10 clinical types described types A3 and D are relatively common isolated forms.Brachydactyly can occur either as an isolated malformation or as a part of a complex malformation syndrome 1 .Our patient was a case of brachydactyly type A2 (BDA2) with only index fi ngers affected.Her family history revealed similarly affected 6 members in four generations.We present this family with this rare disorder.

Case report
A 32-year-old female presented to the emergency department with recurrent paronychia of the right middle fi nger.She was treated surgically.On examination, she was found to have short bilateral index fi ngers in both her hands, present since her birth, without any associated problem.The index fi ngers were symmetrically short with absent middle phalanx and hypoplastic nails (Figure 1).There was no other systemic or skeletal abnormality.The toes were clinically normal.
The patient had a 2-year-old son who had similar abnormality.Her child was examined by the surgical and paediatric teams.The child had normal milestones of development.On examination, he also had no other skeletal abnormality.He was found normal on general and systemic examinations.The index fi ngers were symmetrically short (Figure 2).The toes were clinically normal.On further questioning she mentioned that her 4 other her family members had similar abnormality (Fig 3).Two of them were not alive and the two other members are living in another part of the country.All the affected members who died had death from known causes and they were apparently normal and had reasonably long life.The family is spread over different places in India.Various family members were contacted by telephone and a family pedigree was charted by compiling the history obtained from all the sources.Most of the sources were quite confi dent about their memory.There was no other information available regarding the previous generations.There was no known history of any consanguineous marriage.The patient didn't wish to go for further radiological examination.
BRACHYDACTYLY) BDA2 is characterized by hypoplasia/aplasia of the 2 nd middle phalanx of the index fi nger and sometimes little fi nger.It was fi rst described by Mohr and Wriedt 5 .It is characterized by a triangularshaped middle phalanx in the index fi ngers and second toes.With more severe deformity, the index fi nger is curved radially.Deformity of the 2 nd toe is a more consistent fi nding than deformity of the index fi nger.The big toes show malformation of the proximal phalanx resulting in fi bular deviation of the distal phalanx, while all other toes have rudimentary middle phalanges causing tibial defl ection of their distal phalanges.Temtamy and McKusick 1 reported a family, the fourth in the literature, with 16 affected members in four generations.
The family described here is one of the extremely rare families with brachydactyly type A2.Curiously they all had (at least the two examined) had only index fi ngers involved which is not the more consistent deformity.
It is a very rare digital malformation.There is no epidemiological study found in the literature.Clinical and radiological evaluation of the hands and curved index fi nger, together with the second toe should be done for diagnosis.The characteristic feature is seen as triangular shaped middle phalanx of the index fi ngers and second toes.Studied families demonstrate autosomal dominant inheritance.
Type A2 brachydactyly can be caused by mutation in the human bone morphogenetic protein receptor 1B gene (BMPR1B) on chromosome 4q, that affect cartilage formation in a dominant-negative manner 6 .Kjaer et al 7 found that sparing of the 4 th fi nger distinguishes the Mohr-Wriedt type BDA2 from BDA2 caused by mutations in BMPR1B.
There is no specifi c management or treatment that is applicable to all forms of brachydactyly.Plastic surgical correction is only indicated in patients where hand function is affected or for cosmetic reasons, but is not needed for most of the cases.Sometimes physical therapy and ergotherapy may be required for improving hand function.Prognosis depends on the nature and severity of the abnormalities associated with various syndromes.
The hand phenotype in isolated forms of brachydactyly allows identifi cation of 11 types, with minimal degrees of phenotypic overlap 2 .Normally, the inheritance is of autosomal dominant pattern with variable expression and penetrance.There are extensive numbers of syndromic forms.All the cases of brachydactyly should have thorough clinical evaluation

Discussion
The term brachydactyly is derived from the ancient Greek (brachy: short; dactylos: digit).It indicates shortening of digits due to abnormal development of phalanges, metacarpals, or both.Brachydactyly is one of the various described categories of hand malformations.Although it means "short fi nger", it has a clinical spectrum ranging from minor digital hypoplasia to complete aplasia 2 .
The isolated brachydactyly can be associated with subtle other malformations.It is often associated with hyponychia 3 .Brachydactyly may also be accompanied by other hand malformations, such as syndactyly, polydactyly, reduction defects, or symphalangism.In isolated cases of brachydactyly, are mostly inherited as autosomal dominant with variable expressivity and penetrtance 2 .

Brachydactyly type A2 (BDA2)
[Online Mendelian Inheritance in Man (OMIM): 112600] Synonym: MOHR-WRIEDT TYPE of both hands and feet including radiological evaluation, clinical evaluation of the whole body of the patient, family history (taking non-penetrance into account).Ideally at least all the fi rst degree relatives should have clinical evaluation.Analysis of the available photographs of the dead members of the family should be done.Specifi c investigations should evaluate symptoms from other systems.For research purpose and patient counseling molecular analysis is justifi ed.

Fig 1 :
Fig 1: Hands with short index fi ngers and hypoplastic nails in mother (patient).

Fig 2 :
Fig 2: The hands of the child with hypoplastic index fi ngers.