Human Malformation Syndromes of Defective GLI: Opposite Phenotypes of 2q14.2 (GLI2) and 7p14.2 (GLI3) Microdeletions and a GLIA/R Balance Model.

ABSTRACT

GLI family zinc finger proteins are transcriptional effectors of the sonic hedgehog signaling pathway. GLI regulates gene expression and repression at various phases of embryonic morphogenesis. In humans, 4 GLI genes are known, and GLI2 (2q14.2) and GLI3 (7p14.1) mutations cause different syndromes. Here, we present 2 distinctive cases with a chromosomal microdeletion in one of these genes. Patient 1 is a 14-year-old girl with Culler-Jones syndrome. She manifested short stature, cleft palate, and mild intellectual/social disability caused by a 6.6-Mb deletion of 2q14.1q14.3. Patient 2 is a 2-year-old girl with Greig cephalopolysyndactyly contiguous gene deletion syndrome. She manifested macrocephaly, preaxial polysyndactyly, psychomotor developmental delay, cerebral cavernous malformations, and glucose intolerance due to a 6.2-Mb deletion of 7p14.1p12.3 which included GLI3, GCK, and CCM2. Each patient manifests a different phenotype which is associated with different functions of each GLI gene and different effects of the chromosomal contiguous gene deletion. We summarize the phenotypic extent of GLI2/3 syndromes in the literature and determine that these 2 syndromes manifest opposite features to a certain extent, such as midface hypoplasia or macrocephaly, and anterior or posterior side of polydactyly. We propose a GLIA/R balance model that may explain these findings.