MOLECULAR ANALYSIS OF SPLIT HAND/FOOT MALFORMATION (SHFM) AT THE SHFM3 AND SHFM5 LOCI

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

Cox regression models predicting death or non-fatal myocardial infarction (N = 6,126, N events = 1,769).

<p> Note: The model including adjustment covariates included all predictors simultaneously.</p

Clinical Characteristics by sex and <i>5HTR2C</i> rs6318 Ser23 C and Cys23 G allele.

<p>^a p-value derived from unadjusted linear model;^b p-value derived from age-adjusted logistic regression model;^c p-value derived from age-adjusted linear model;^d p-value was derived from age-adjusted ordinal logistic regression model with number of diseased vessels modeled as an ordinal variable ranging from 0 to 3. Note. </p

Kaplan-Meier curves illustrating the risk of death or myocardial infarction for each rs6318 genotype in Women (panel a) and Men (panel b).

<p>Using pre-specified contrasts in a Cox regression model adjusted for covariates, differences were statistically significant when comparing: male Ser23 C hemizygotes and female Ser23 C homozygotes to all Cys23 G carriers (p  = .005); male Ser23 C hemizygotes to male Cys23 G hemizygotes (p  = .022), and female Ser23 C homozygotes to female Cys23 G carriers (p  = .024).</p