Genetic Analysis of Craniosynostosis, Philadelphia Type

Overview

This study will try to find the gene changes responsible for the birth defects in craniosynostosis, Philadelphia type. Craniosynostosis syndromes are a group of conditions that result from closure of one or more of the fibrous joints between the bones of the skull before brain growth is complete. Because of the premature closure, the brain is not able to grow in its natural shape; instead, it compensates with growth in areas of the skull where the joints have not yet closed. The defects in raniosynostosis, Philadelphia type, include skull malformations and webbing of the fingers and toes. Gene changes known to be involved in other craniosynostosis syndromes have not been found in the Philadelphia type syndrome. Therefore, finding the genetic basis of this disorder will provide important new information regarding craniofacial and limb development. This study includes members of a single large family affected with craniosynostosis, Philadelphia type. Participants have 1 to 2 teaspoons of blood drawn for genetic studies. A second blood sample may be requested for further research. Some blood may be used to establish a cell line for later studies. This involves growing the white blood cells from the blood sample. The cells can be kept in the laboratory to make more DNA or can be frozen for later use in craniosynostosis studies. Patients may also have their medical records reviewed.

The objective of this study is to determine the molecular basis of craniosynostosis, Philadelphia type. Previous studies by our lab have excluded FGFR1, FGFR2 and FGFR3, the causative genes of most hereditary craniosynostosis syndromes. In the five generation kindred previously reported we have conducted a genome-wide linkage analysis. We have identified four regions linked to this disorder, namely on 2q, 12q, 20q and 22q. Interestingly, syndactyly 1A, a phenotypically similar disorder, demonstrates an overlapping linkage region in two studies. Screening of candidate genes in the redion has excluded ten candidate genes, including IHH, IGFBP2 and IGFBP5. This protocol is primarily for research purposes. Research subjects may receive benefit from knowing that this research may help other families in the future. Results will be discussed with the primary physician who is a trained medical geneticist. We will emphasize that these are only preliminary findings, that they are not CLIA-approved, and must not be disclosed to the patient or included in the medical record. Repeat testing in a CLIA-approved lab would be required before the specific genetic information could be shared with the patient and family.