Dorsal dimelia of a thumb

Circumferential Nail

“…Upper limb development, including the digits, occurs in three axes: dorsoventral, proximodistal, and anteroposterior [7]. In our case, the duplicated thumb reflected abnormality in all three: dorsal dimelia (dorsoventral axis), preaxial polydactyly (anteroposterior axis) and triphalangism (proximodistal axis).…”

“…In our case, the duplicated thumb reflected abnormality in all three: dorsal dimelia (dorsoventral axis), preaxial polydactyly (anteroposterior axis) and triphalangism (proximodistal axis). The role of several genes (BMP4, BMP7, BMP-1A, En-1, Wnt7a, Lmx-1) in the development of limb bud has been well described in the literature [7, 10, 11]. Stimulation of BMP (bone morphogenic protein) receptor-1A (BMPR-1A) by BMP4 and BMP7 results in an induction of the transcription factor En-1 in the ventral ectoderm of the limb bud.…”

“…CN more commonly involves the ring and little finger nails, rarely being reported on the thumb [7]. Due to a paucity of reports, the exact incidence, gender predisposition, predisposing factors as well as long-term outcomes or pathogenic mechanisms for this condition are not well understood.…”

“…It has also been argued that any loss-of-function or gain-of-function mutations in these genes should ideally result in expression of the abnormality in all fingers. Al-Qattan and Kfoury [7] proposed that sporadic cases might result from stochastic developmental error.…”

Re: Al-Qattan MM. Concurrent dorsal dimelia in 160 consecutive patients with congenital anomalies of the hands and feet. J Hand Surg Eur 2013. Epub ahead of print 20 December 2013. DOI: 10.1177/1753193413517458

“…We base this on both the current article and an earlier one (Al-Qattan, 2013; Al-Qattan and Kfoury, 2011). Table 3 of the current article noted 11 patients with ‘Dorsal dimelia and concurrent congenital anomalies in all previously reported cases in the literature’ (giving a total of 16 cases including the five cases newly reported in this article).…”