A newly recognized syndrome involving limbs, pelvis, and genital organs or a variant of Al-Awadi/Raas-Rothschild syndrome?

A case of severe proximal focal femoral deficiency with overlapping phenotypes of Al-Awadi-Raas-Rothschild syndrome and Fuhrmann syndrome

Proximal focal femoral deficiency (PFFD) is a heterogeneous disorder characterized by various degrees of femoral deficiencies and associated anomalies of the pelvis and lower limbs. The etiology of the disease has not been determined. We report on a 3-year-old boy with severe PFFD, who showed almost completely absent femora and fibulae, malformed pelvis and ectrodactyly of the left foot. These features were partially overlapped with those of Al-Awadi-Raas-Rothschild syndrome or Fuhrmann syndrome, both of which are caused by WNT7A mutations. Molecular analysis of our case, however, demonstrated no disease-causing mutations in the WNT7A gene.

Al-Awadi/Raas-Rothschild syndrome: two new cases and review

Al-Awadi/Raas-Rothschild syndrome, an autosomal recessive disorder, is characterized by severe malformations of the upper and lower limbs, and a hypoplastic pelvis. We describe two new cases with the typical manifestations, report some new findings, review the relevant literature, and present minimal criteria for the diagnosis. A single homozygous WNT7A mutation was identified by Woods et al. [2006]: 1179C --> T, resulting in Arg292Cys with complete loss of WNT7A function.

Avian pelvis originates from lateral plate mesoderm and its development requires signals from both ectoderm and paraxial mesoderm

The pelvic girdle is composed of three skeletal elements: ilium, pubis, and ischium. In comparison with other parts of the postcranial skeleton, its development is not well known to date. To elucidate the embryonic origin of the avian pelvic girdle and the signaling centers that control its development, we have performed extirpation and quail-to-chick grafting experiments. The results reveal that the entire pelvic girdle originates from the somatopleure at somite levels 26 to 35. No somitic cell contribution to skeletal elements of the pelvis has been detected. Removal of the surface ectoderm covering the lateral plate mesoderm has revealed that ectodermal signals control the development of the pelvic girdle, especially the formation of the pubis and ischium. The impaired development of the ischium and pubis correlates with the downregulation of Pax1 and Alx4, two transcription factors that control the normal development of the ischium and pubis. Although of somatopleural origin, the development of the ilium depends on somitic signals. Insertion of a barrier between somites and somatopleure disrupts the expression of Emx2 and prevents normal development of the ilium but does not affect the expression of Pax1 or Alx4 and the development of the pubis and ischium. Thus, the development of the ilium, but not of the pubis and ischium, depends on somitic and ectodermal signals.