Although the pathology of<unk>  is unknown, it is a heritable autosomal recessive disorder. Parents of people with<unk>  are sometimes related, and there have been several cases of it occurring in monozygotic twins, siblings, and cousins. There is great variability in symptoms between cases, especially in intelligence. Although there is much evidence that<unk>  is genetic, the symptoms are similar to fetal alcohol syndrome. Further studies are needed to determine whether alcohol influences whether<unk>  manifests in people who are genetically vulnerable. Breakdown of chromosomes is known to occur. Growth hormone<unk>  is accompanied by a deficiency in growth hormone. People with<unk>  have stunted growth, and growth hormones are secreted by the anterior pituitary of the brain. The main function of the anterior pituitary is to increase height during development. Other functions include regulating the immune system, increasing calcium retention, increasing muscle mass and stimulating gluconeogenesis. A deficiency in growth hormone may be caused by genetic mutations, malformations of the hypothalamus or pituitary gland during development, or damage to the pituitary. In<unk> , the cause is likely the underlying mutations or disruption of brain structures during development. Growth hormone deficiency also correlates with low levels of IgG antibodies, a condition found in<unk>  patients. DNA repair defect A fibroblast cell line developed from a patient with<unk>  was found to be hypersensitive to ionizing radiation and several other DNA damaging agents due to a defect in the repair of DNA double strand breaks. The DNA repair defect was traced to mutations in the DNA ligase IV LIG4 gene. This finding suggests that the molecular basis for at least a subset of<unk>  cases is a DNA ligase IV defect. Relationship to Smith–Lemli–Opitz syndrome Researchers are investigating the genetic similarities between<unk>  and Smith–Lemli–Opitz syndrome (SLOS). Patients with SLOS and<unk> s have many of the same abnormalities, and the two disorders are hypothesized to be linked. Two characteristics of SLOS are a low cholesterol level and a high 7-Dehydrocholesterol level. Cholesterol is essential for several bodily functions, including maintaining cell membrane structure, embryogenesis, and synthesis of steroid and sex hormones. Impaired cholesterol synthesis or transport may account for most of the symptoms of both SLOS and<unk> . Although only a few patients with<unk>  have been identified with altered cholesterol levels, researchers are exploring whether<unk> , like SLOS, is linked to a defect in the cholesterol biosynthetic pathway. The pathology of<unk>  is still unclear because of its rarity and the wide array of associated symptoms. Several studies have focused on different aspects of the disorder to try to find its exact cause and expression. One study examined the specific oral features in one patient. Another found abnormalities in the brain, such as corpus callosum dysgenesis, an underdeveloped anterior pituitary and a brain stalk with an ectopic (misplaced) posterior pituitary.
Dubowitz syndrome
Keppen–Lubinsky syndrome
XXYY syndrome
Foster Kennedy syndrome
Ring chromosome 20 syndrome
XYYYY syndrome
Goldberg–Shprintzen syndrome
XYYY syndrome