symptoms from this abnormality. Other skeletal defects common in ALGS patients are spina bifida and the fusion of vertebrae. Most of the ophthalmological defects affect the anterior chamber of the eyeball, including Axenfeld's anomaly and Rieger anomaly, but retina pigment changes are also common. These anomalies can be beneficial in diagnosing Alagille syndrome. Many people with ALGS have similar facial features, including a broad, prominent forehead, deep-set eyes, and a small pointed chin. While these distinct facial features are often presented in ALGS patients, the features are presumably not due to Alagille syndrome, but they are characteristic of patients with intrahepatic cholestatic liver disease. So while these facial characteristics are extremely common in ALGS patients, it is because many patients experience extreme liver complications or liver failure, but it is not caused by the disease itself. The kidneys may also be affected because the mutations in JAG1 and NOTCH2 often lead to renal dysplasia, deformed proximal tubules, or lipidosis caused by the hindrance of lipid metabolism. Genetics ALGS is caused by loss of function mutations in either JAG1 (Jagged1) or NOTCH2 (Notch homolog 2). In the majority of people with ALGS, the gene mutation occurs in the JAG1 gene. The JAG1 mutation is either intragenic and found on chromosome 20p12, or it is a deletion of the entire JAG1 gene. Mutations in NOTCH2 are much less likely to cause Alagille syndrome, but the primary type of ALGS-causing mutation in NOTCH2 is a missense mutation. A missense mutation is a point mutation that changes one nucleotide, which results in a codon that codes for the wrong amino acid. Alagille syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to cause the disorder. The "autosomal" aspect of the disease means that the gene mutation occurs in an autosome, which is one of the 44 chromosomes in the human body that is not a sex chromosome (chromosome X or Y). Although the majority of cases are due to the autosomal dominant gene, there have been reports of a rare, autosomal recessive version of the disease. In the autosomal recessive case, the ALGS patient must inherit two mutated genes: one from each parent. Although about 40% of the mutations are inherited from affected parents, most cases result from new, acquired mutations. These are caused by environmental factors that mutate one copy of the gene. Environmental