children s health issues
Overview of Chromosome and Gene Disorders
Gene Abnormalities
 create a variant of that gene that may affect how the gene works. These changes do not affect the structure of the chromosomes and thus cannot be seen on karyotype analysis or other chromosomal tests. More specific genetic testing is required. Some variants in a gene cause no problems and some cause few or only mild problems. Other variants cause serious disorders such as Sickle Cell Disease , It remains unclear how most variants occur, but most are thought to appear spontaneously. Some substances or agents in the environment are capable of damaging and causing variation in genes. These substances are called mutagens. Mutagens, such as radiation, ultraviolet light, and certain medications and chemicals, can cause some cancers and Overview of Birth Defects . A variant in the genes in a sperm or egg can be passed from parent to child. Variants of genes in other cells may cause disease that is not passed down to children (because the sperm or eggs are not affected). Having two copies of an abnormal gene can lead to serious diseases or conditions, such as Cystic Fibrosis (CF) or 