Midfacial hypoplasia (MFH) is a disorder of severe underdevelopment of the upper face. This problem is significant because MFH can lead to a deformity that impedes chewing, feeding, and breathing. Although it is known that MFH can occur due to gene mutations, teratogens, and trauma, it is unknown how these insults affect anterior growth of the face. Using a novel pig model, this project aims to isolate the location of structural changes to the skull caused by MFH. We first determined if MFH in pigs is isolated to the face, and then identified the specific bones of the face that are altered by MFH. To determine if MFH is isolated to the face, we measured and compared the length of the braincase, mandible, and upper face in pigs with MFH to that of normal pigs. We then measured and compared the dimensions of individual facial bones, including the maxilla, premaxilla, nasal bone, lacrimal bone, and zygoma. All measurements were done on dry skulls with calipers and compared using t-tests. Our initial qualitative comparison of 6 normal and 6 affected pigs has found that MFH is isolated to the face, with the premaxilla, maxilla, nasal bone, and lacrimal bone shortened. The zygoma and palatine bones were normal. We hypothesize that our qualitative comparison of approximately 35 MFH pigs and 115 normal pigs will show similar results. Identifying the bones affected by MFH will help us to hone in on the specific tissue changes and mechanisms that cause MFH, and to discover better treatments for this condition.

Midfacial Hypoplasia (MFH) is an underdevelopment of the upper jaw, cheekbones and eye sockets. MFH sometimes results in difficulty in breathing in children. Severe cases are treated with serious surgeries that often have unsuccessful outcomes. Understanding the consequences of MFH is a critical step in treating this disorder. The goal of my project is to use Yucatan pigs as a model for MFH. MFH is common in Yucatan pigs and resembles MFH in humans which makes it useful for a model. In addition, pigs resemble humans in physiology, anatomy and growth. Humans with MFH have reduced nasal airway capacity, and this is likely true for Yucatan pigs as well. The nature of airway deficiency is not fully understood, but it may be due to reduction of the nasal airway surface area. Reduction in the surface area would hamper the ability of the nasal passage to regulate air temperature and humidity. I hypothesize shortening of the nasal cavity in MFH reduces the surface area inside the cavity. Using CT scans from pigs, I measured the dimensions of the nasal passages via Metamorph and Photoshop software. Based on my hypothesis, I expect to observe lower surface area in pigs with MFH. If a correlation between MFH and surface area is found, this research will provide new insights about the consequences of MFH that will be relevant for better treatment of this disorder.