Terminal transverse limb defects with "nubbins"

A terminal transverse limb defect with absence of the forearm and hand or just the hand is an uncommon limb deformity in an otherwise healthy newborn. Most of the affected infants also have tiny digit-like nubbins on the stump of the affected limb, a finding that could represent an attempt at regeneration following vascular obstruction in early limb development.

One hundred ninety-four newborn infants with a limb deficiency were identified among 289,365 births in an active malformations surveillance program at Brigham and Women's Hospital in Boston, MA from 1972 to 2012. Twenty-eight infants with terminal transverse limb defects were identified.

Twenty-four had tiny digit-like nubbins (0.5 cm in length) on the stump at one of three levels: the proximal portion of the forearm, the wrist or the forefoot. The examination of the placentas of eight affected infants showed no evidence of amnion rupture. Three of these 28 infants had associate chromosome abnormalities: trisomy 21, chromosome 11q deletion and the deletion of 22q11.2.

Terminal transverse limb defects reflect failure of early limb development. Awareness of this phenotype at birth, or when identified by ultrasound screening, can provide more accurate counseling than occurs with the more common misdiagnosis of "amniotic band syndrome."