Mouse Fzd4 maps within a region of chromosome 7 important for thymus and cardiac development

The cardiac neural crest (CNC) plays a central role in development of the t hymus gland and cardiovascular system. Through morphological and histologic al characterization of embryos homozygous for the Del(7)Tyr(c-112K) and Del (7)Tyr(c-3H) albino deletions, we identified abnormalities that are consist ent with aberrant development of tissues requiring ohio contributions. The defects include incompletely penetrant heart and great vessel patterning de fects and hypoplastic thymus glands. The CNC phenotype is complemented by t he partially overlapping deletion De1(7)Tyr(c-23DVT). Combined, these resul ts suggest that a functional region necessary for development of CNC derive d tissues is located between the Del(7)Tyr(c-23DVT) and Del(7)Tyr(c-112K) d istal deletion breakpoints. This interval encompasses a functional region p reviously identified as important for juvenile survival (juvenile developme nt and fertility, jdf). Using deletion mapping, we localized the Frizzled4 (Fzd4) gene to the jdf/thymus and cardiac development intervals. (C) 2000 W iley-Liss, Inc.