Date of Award

12-2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Genetics

Advisor

Schwartz, Charles E

Committee Member

Everman , David

Committee Member

Chapman , Susan

Committee Member

Frugoli , Julia

Committee Member

Abbott , Albert

Committee Member

Maze , Jennifer

Abstract

Split hand/foot malformation (SHFM) is a congenital limb malformation observed in humans characterized by a reduction or loss of the central digits of the hands and/or feet. The condition affects one in every 8,500 to 25,000 births, accounting for 8-17% of all limb reduction defects. A tandem duplication of approximately 500 Kb has been determined to be the causative mutation at the SHFM3 locus. Patients that are heterozygous for this duplication have three copies of the genes BTRC, POLL, and DPCD as well as an extra copy of exons 6-9 of FBXW4. The SHFM3 critical region also contains the FGF8 and SUFU genes. The aim of this study was to determine if and where these genes are expressed during normal limb development in the chicken. All the genes except poll at embryonic day 6 (E6) were detected by RT-PCR of cDNA from the limbs of E3-E13 embryos. In situ hybridization of paraffin sections from limbs of the chicken at E6 and E8 showed that BTRC, DPCD, FBXW4, FGF8, and SUFU are expressed in the region of the limb where digit formation occurs. Taken together, these data suggest that all of the genes, with the exception of POLL, may play a role in the development and patterning of the limb. The duplication within this region found in patients with SHFM could cause the phenotype by altering the expression of these genes, either through an increase in expression of the duplicated genes, the removal of a gene from its regulatory element, or a combination of the two.
This study also screened a cohort of patients with SHFM with an unknown molecular cause for mutations in two enhancer elements, one located within intron 4-5 of BTRC in the SHFM3 locus, and the other located within the SHFM5 locus. Sequencing of these elements found no damaging mutations in any patient.

Included in

Genetics Commons

Share

COinS