Genetics
There is still some discussion on whether FND is sporadic or genetic. The majority of FND cases are sporadic. Yet, some studies describe families with multiple members with FND. Gene mutations are likely to play an important role in the cause. Unfortunately, the genetic cause for most types of FND remains undetermined. Frontorhiny
The cause of frontorhiny is a mutation in the ALX3 gene. ALX3 is essential for normal facial development. Different mutations can occur in the ALX3 gene, but they all lead to the same effect: severe or complete loss of protein functionality. The ALX3 mutation never occurs in a person without frontorhiny. Acromelic frontonasal dysostosis
Acromelic frontonasal dysostosis is caused by a heterozygous mutation in the ZSWIM6 gene. It is thought that acromelic frontonasal dysostosis occurs due to an abnormality in the Sonic Hedgehog (SSH) signaling pathway. This pathway plays an important role in developing the midline central nervous system/craniofrontofacial region and the limbs. Hence, it is plausible that an error in the SSH pathway causes acromelic frontonasal dysostosis, because this syndrome not only shows abnormalities in the midfacial region, but also in the limbs and CNS. Diagnostics
The main diagnostic tools for evaluating FND are X-rays and CT-scans of the skull. These tools could display any possible intracranial pathology in FND. For example, CT can be used to reveal widening of nasal bones. Diagnostics are mainly used before reconstructive surgery, for proper planning and preparation.Prenatally, various features of FND (such as hypertelorism) can be recognized using ultrasound techniques.
Toluene is a component of high-octane gasoline; xylene is used in the production of polyester fibers and resins. trichloroethylene, an industrial degreasing solvent
Organophosphate pesticides

Head trauma
There can be damage either to the ear itself or to the central auditory pathways that process the information conveyed by the ears. People who sustain head injury are susceptible to hearing loss or tinnitus, either temporary or permanent. Contact sports like football (U.S. NFL), hockey and cricket have a notable incidence of head injuries (concussions). In one survey of retired NFL players, all of whom reported one or more concussions during their playing careers, 25% had hearing loss and 50% had tinnitus. Perinatal conditions
These are much more common in premature babies, particularly those under 1500 g at birth. Premature birth can be associated with problems that result in sensorineural hearing loss such as anoxia or hypoxia (poor oxygen levels), jaundice, intracranial haemorrhages, meningitis. Fetal alcohol syndrome is reported to cause hearing loss in up to 64% of infants born to alcoholic mothers, from the ototoxic effect on the developing fetus, plus malnutrition during pregnancy from the excess alcohol intake. Iodine deficiency / Hypothyroidism
Iodine deficiency and endemic hypothyroidism are associated with hearing loss. If a pregnant mother has insufficient iodine intake during pregnancy it affects the development of the inner ear in the foetus leading to sensorineural deafness. This occurs in certain areas of the world, such as the Himalayas, where iodine is deficient in the soil and thus the diet. In these areas there is a high incidence of endemic goitre.