Cleft Candidate Genes and Their Products in Human Unilateral Cleft Lip Tissue

Abstract

Cleft lip and palate are common congenital pathologies that affect the human population worldwide. The formation of cleft lip is associated with multiple genes and their coded proteins, which regulate the development of craniofacial region, but the exact role of these factors is not always clear. The use of morphological studies for evaluation of human cleft-affected tissue has been limited because of insufficiency of available pathological material. The aim of this study was to detect and compare the immunohistochemical expression of cleft candidate gene coded proteins (DLX4, MSX2, HOXB3, SHH, PAX7, SOX3, WNT3A, and FOXE1) in the non-syndromic unilateral cleft lip patient tissue and control group tissue. A semiquantitative counting method was used to evaluate the tissue in biotin-streptavidin-stained slides. Statistically significant differences between the patient and control groups were found for the number of immunoreactive structures for SHH (p = 0.019) and FOXE1 (p = 0.011) in the connective tissue and SOX3 (p = 0.012) in the epithelium. Multiple statistically significant very strong and strong correlations were found between the immunoreactives in cleft-affected tissue. These significant differences and various correlations indicate that multiple morphopathogenetic pathways are possibly involved in unilateral cleft lip pathogenesis. Therefore, we further discuss these possible interactions.

The presence and distribution of various genes in postnatal CLP-affected palatine tissue

“…Furthermore, Shh signaling seems to promote pericyte-like function in cranial neural crest cells, which is necessary for microvascular stability and correct facial morphogenesis [ 63 ]. SHH has been associated with orofacial clefts in mice and human studies [ 26 – 30 ]. In our research, only 6 tissue samples had varying amounts of SHH gene-containing cells in the epithelium, but the results were not statistically significant.…”

“…Overall, there is a very limited amount of studies observing an association between SOX3 and orofacial clefts. For example, one study reported increased SOX3-positive immunoreactive structures within human unilateral cleft lip [ 30 ]. Therefore, while our data indicates that neither SHH nor SOX3 played a role in our study group, we cannot categorically exclude their role from CLP morhopathogenesis.…”

“…Furthermore, in human studies, different SHH etiological susceptibility variants have been reported [ 28 , 29 ]. Additionally, statistically significant differences in SHH protein expression between the control group and OFC patients have been observed in immunohistochemically stained and examined tissue samples [ 30 ].…”

“…Similarly to mice, SOX3 mutations in humans also cause a variable phenotype [ 37 – 39 ]. Furthermore, increased SOX3-positive immunoreactive structures within human unilateral cleft lip have been reported [ 30 ].…”

Histological and Immunohistochemical Studies to Determine the Mechanism of Cleft Palate Induction after Palatal Fusion in Mice Exposed to TCDD

“…Cleft palate is thought to be an abnormality caused during palate development via one of the following mechanisms the left and right palatine processes are not elevated, and horizontal dislocation does not occur [6]; palatine processes are elevated but do not grow horizontally and do not make contact [7]; or left and right palatine processes make contact and do not fuse because of horizontal dislocation and horizontal growth of the palatine processes [8,9] and cleft palate, resulting in separation of the palate after fusion of the palatine processes [10,11]. Genetic factors include such as mutations in TGFβ, MSX1, TBX22, IRF6, and MEOX2, and Hoxc, HOXB3, and TFAP2A [12][13][14][15][16][17]. The multifactorial threshold theory suggests that environmental factors, such as alcohol and tobacco consumption, maternal obesity, and exposure to chemicals such as TCDD and vitamin A [18][19][20] interact to cause cleft palate once a certain threshold is exceeded.…”