Mesomelic Dysplasia, Kantaputra Type

Mesomelic dysplasia Kantaputra type (MDK) is a rare skeletal disease characterized by symmetric shortening of the middle segments of limbs and short stature.

Epidemiology

It has been described in five families.

Clinical description

In the upper limbs, the ulnae are very short, and the radii are bowed. The distal humerus has a dumbbell shape. The hands show progressive flexion contractures of the proximal interphalangeal joints. In the lower limbs, feet are fixed in plantar flexion so that the patients walk on their toetips. The prominent distal fibula on the ventral aspect is common and considered a hallmark. Fibula, talus and calcaneus are small and fibulo-calcaneal synostosis is a characteristic feature. Carpal and tarsal synostoses are observed in some individuals. All affected patients have normal craniofacial features and intelligence.

Etiology

Using microarray-based comparative genomic hybridization (array-CGH), two microduplications have been identified on chromosome 2 (2q31.1-q31.2), separated by a segment of normal copy number. The more centromeric duplication encompasses the HOXD cluster and it is proposed that duplications cause dysregulation of HOXD gene expression.

Genetic counseling

In all families, the condition is transmitted as an autosomal dominant trait.