Antenatal Diagnosis of Bilateral Proximal Femoral Focal Deficiency (PFFD)

Proximal femoral focal deficiency (PFFD) is a rare skeletal dysplasia, characterized by hypoplasia of the subtrochanteric femur with variable degrees of shortening of the femoral shaft. There are numerous gene e.g. TBX4, FGF, FGFR, TP63 and HOX responsible for limb formation, type and its shape. Normal limb development is three dimensional; proximodistal axis regulated by AER; anteroposterior axis (preaxial/postaxial) governed by SHH with ZPA and dorsoventral axis controlled by LMX1B. Primigravida with diamniotic dichorionic twins in first trimester was found to have absent right femur, fibula and left femural bone with hypoplastic right foot in one foetus. Right tibia, both left tibia and fibula and left foot were visualized normally. Bilateral humerus, radius and ulna along with digits were visualized with no evidence of oligodactyly. Twin II had no major limb reduction defect. Both nasal bones, hard palate were visualized; nuchal translucency was within normal range for the foetus of 13 weeks 3 days of duration; suggestive of bilateral PFFD; Aitken type 4 in Twin I. We are the first to describe bilateral PFFD in the first trimester of pregnancy. Nuchal scan provides a window of opportunity to the foetal medicine specialists to screen the foetus for major congenital anomalies and to proceed with further investigation or with selective reduction as in this case so as to optimize the pregnancy outcome. Identification of PFFD at 13 weeks with foetal reduction helped in minimizing the risk to the surviving foetus.