Introduction

Neural tube defects (NTDs) are one of the most common congenital abnormalities in mammalian vertebrates, occurring in 1-2 infants per 1,000 births. NTDs are a heterogeneous group of congenital malformations that affect the brain and spinal cord (3). NTDs cover a broad spectrum of phenotypes that are characterized by the incomplete closure of mesenchymal bone and nervous tissue of the spine. A general term used for congenital malformations of the spine is spinal dysraphism. There are many different types of dysraphisms, ranging from closed spinal dysraphisms that are only detected externally by scaly tissue along the midline of the body, to fatal and severe open spinal dysraphisms such as spinal bifida and craniorachischisis(3,7).
 * What Are Neural Tube Defects? **

To understand better how these malformations occur and how //VANGL1// and //VANGL2// genes affect the developmental stage of growth a general review of developmental physiology is needed.

During this period of development the germ layers of the embryo are formed and the pathway to formation of the body is established. Many genes and gene families are involved in gastrulation; this is the groundwork for all future organism development. The primary germ layers (endoderm, mesoderm, and ectoderm) are formed. The ectoderm is the exterior germ layer and forms the skin, brain, and spinal cord (6). Neurulation is the development of the neural tube which gives rise to the spinal cord and brain. The neural plate forms, the cells change shape and elongate longitudinally. This process is called convergent extension. The edges of the plate fold in and meet midway forming a tube that lies directly over the notochord. The notochord gives rise to the vertebral column, which protects the spinal cord (6).
 * __Step1: Gastrulation __**
 * __Step 2: Neurulation __**



Neural tube disorders involve complex molecular mechanisms that have both genetic and environmental conditions, a multifactoral condition (3). The genes whose products function in a pathway to establish planar cell polarity play a huge role in development of the neural tube. Mutations of these genes in vertebrates results in neural tube defects. Planar cell polarity (PCP) is an important biochemical pathway for vertebrae neurulation. In order for neural tube closure in the hindbrain, the floor plate narrows by convergent extension, if there is no convergent extension the folds remain too far apart to fuse. Studies in genetics and biochemistry have shown that critical interactions between molecules i.e. //disheveled// (//Dvl//) and //Strabismus/Van gogh// (//Stbm/Vang//) interact to create the planar cell polarity needed for normal development (5). This presentation will focus on the mammalian orthologs of //Stbm/Vang//, //VANGL1// and //VANGL2// genes. Home Proteins in Development

 3.Torban, Elena, Anne-Marie Patenaude, and Et.al. “Genetic interaction between members of the Vangl family causes neural tube defects in mice.” Proceedings of the National Academy of Sciences of the United Stats of America 105.9 (2008): 3449-3454. EBSCO Host. Web. 8 Oct. 2010. []. 5.Doudney, K., G. E. Moore, and P. Ybot-Gonzalez. “Analysis of the Planar Cell Polarity Gene Vangl2 and its Co-Expressed Paralogue Vangl1 in Neural Tube Defect Patients.” American Journal of Medical Genetics 136A (2005): 90-92. EBSCO Host. Web. 10 Oct. 2010. []. 6.Frederick, Martini, and Judi L. Nath. Fundamentals of Anantomy and Physiology. San Francisco: Pearson Benjamin Cummings, 2009. Print. 7. “Neuroradiology Spinal Dysraphism.” GE Healthcare. Bio-Sciences Europe, 2012. Web. 28 Nov. 2010. [.



** ﻿ **