In this scenario, the brain sends a lot of hormonal signals (high gonadotropin), but the gonads are unable to respond to said signals causing hypergonadotropic hypogonadism. Hypergonadotropic hypogonadism can be caused by congenital defects or acquired defects. Congenital disorders
Congenital diseases include untreated cryptorchidism where the testicles fail to descend from the abdomen. Other congenital disorders are genetic in nature. In males, there can be deformities in the seminiferous tubule as in Klinefelter syndrome (most common cause in males), defects in the production of testicular steroids, receptor mutations preventing testicular hormones from working, chromosomal abnormalities such as Noonan syndrome, or problems with the cells making up the testes. Females can also have chromosomal abnormalities such as Turner syndrome (most common cause in girls), XX gonadal dysgenesis, and XY gonadal dysgenesis, problems in the ovarian hormone synthesis pathway such as aromatase deficiency or congenital anatomical deformities such as Müllerian agenesis. Acquired disorders
Acquired diseases include mumps orchitis, Coxsackievirus B infection, irradiation, chemotherapy, or trauma; all problems causing the gonads to fail. Genetic or acquired defect of the hormonal pathway of puberty (hypogonadotropic hypogonadism)
The hypothalamic–pituitary–gonadal axis can also be affected at the level of the brain. The brain does not send its hormonal signals to the gonads (low gonadotropins) causing the gonads to never be activated in the first-place resulting in hypogonadotropic hypogonadism. The HPG axis can be altered in two places, at the hypothalamic or at the pituitary level. CNS disorders such as childhood brain tumors (e.g.
Sensory processing is often affected, especially the vestibular system. A high pain threshold is often observed. If speech develops, it is often echolalic but some individuals do grasp some language. With a severely affected person there may be an inability to walk or talk. Genetics
Generally, idic(15) is not inherited; it is said to appear de novo, in one member of the family, by chance. In most cases, the abnormal chromosome is generated in the mothers germ cells: the oocytes. This finding is due to ascertainment bias; cases with maternally derived idic(15) usually have clinical findings and attract attention, but those with paternally derived idic(15) usually do not. Thus, diagnosed cases are usually patients where the duplicated material is derived from the mothers egg cell rather than the fathers sperm cell.People with idic(15) have extra genetic material that has developed from chromosome 15. The material usually exists as a little extra chromosome 15; sometimes called a marker chromosome or an extra structurally abnormal chromosome (ESAC). The marker usually exists as an isodicentric chromosome; i.e. 2 copies of a specific part of the long arm of chromosome 15q11.2-q13.1 that is mirrored and doubled, with 2 centromeres and 2 DNA satellites. The smallest markers appear to be harmless and they may go undetected. However, if they are large enough to contain a number of important genes, they may result in "idic(15) syndrome" which is characterized by learning disabilities, autism and other neurological symptoms.