The gene for Darwin's tubercle was once thought to be inherited in an autosomal dominant pattern with incomplete penetrance, meaning that those who possess the allele (version of a gene) will not necessarily present with the phenotype. However, genetic and family studies have demonstrated that the presence of Darwin's Tubercle may be more likely to be influenced by one's environment or developmental accidents than it is by genetics alone. There is no clear argument for whether the trait has significance in sexual dimorphism studies or age related studies. In some studies, there is clear data that Darwin's tubercle is not associated with sex. In contrast, others indicate that there is a correlation with sexual dimorphism between men and women, where men tend to have the tubercle more than women in some populations. Two studies indicate that older men tend to have greater expression of Darwin's tubercle than do older women.

The feature is present in approximately 10.4% of the Spanish adult population, 40% of Indian adults, and 58% of Swedish school children. This acuminate nodule represents the point of the mammalian ear. The trait can potentially be bilateral, meaning present on both ears, or unilateral, where it is only present on one ear. There is mixed evidence in regard to whether the bilateral or unilateral expression is related to population, or other factors. Some populations express full bilaterality, while others may express either unilateral or bilaterality. However, bilaterality appears to be more common than unilateral as it pertains to the expression of the trait.

Inverse Marcus Gunn phenomenon is a rare condition that causes the eyelid to fall upon opening of the mouth. In this case, trigeminal innervation to the pterygoid muscles of the jaw is associated with an inhibition of the branch of the oculomotor nerve to the levator palpebrae superioris, as opposed to stimulation in Marcus Gunn jaw-winking.

The cause of multicystic dysplastic kidney can be attributed to genetics. Renal dysplasia can be a consequence of a genetic syndrome, which in turn may affect the digestive tract, nervous system, or other areas of the urinary tract. If the mother had been taking certain prescription drugs such as those for hypertension, this may be a precipitating factor as well.

Marcus Gunn phenomenon, also known as Marcus Gunn jaw-winking or trigemino-oculomotor synkinesis, is an autosomal dominant condition with incomplete penetrance, in which nursing infants will have rhythmic upward jerking of their upper eyelid. This condition is characterized as a synkinesis: when two or more muscles that are independently innervated have either simultaneous or coordinated movements.

Common physiologic examples of synkineses occur during sucking, chewing, or conjugate eye movements. There are also several abnormal cranial nerve synkineses, both acquired and congenital. Marcus Gunn jaw-winking is an example of a pathologic congenital synkinesis.

First described by the ophthalmologist Marcus Gunn in 1883, this condition presents in approximately 5% of neonates with congenital ptosis. This condition has been associated with amblyopia (in 54% of cases), anisometropia (26%), and strabismus (56%).

Individuals with CAVD can reproduce with the assistance of modern technology with a combination of testicular sperm extraction and intracytoplasmic sperm injection (ICSI). However, as the risk of either cystic fibrosis or renal agenesis is likely to be higher in the children, genetic counseling is generally recommended.

The cause of this condition is not known. A genetic basis is suspected. More than one case have been reported in three families.

Say syndrome is a condition characterized by bilateral acromial dimples.

In 80% of cases, the parotid gland is affected. Lacrimal glands are also affected.

There are two main populations of CAVD; the larger group is associated with

cystic fibrosis and occurs because of a mutation in the CFTR gene, while the smaller group (estimated between 10 and 40%) is associated with Unilateral Renal agenesis (URA). The genetic basis of this second group is not well understood.

Mutation of the CFTR gene is found to result in obstructive azoospermia in postpubertal males with cystic fibrosis. Strikingly, CAVD is one of the most consistent features of cystic fibrosis as it affects 98-99% of individuals in this CF patient population. In contrast, acute or persistent respiratory symptoms present in only 51% of total CF patients.

In the subset of males with both CBAVD and URA, the CFTR mutation has been shown to occur at a rate only slightly higher than the overall population. Thus, McCallum, et al. have suggested another mutation may be responsible for this condition.

In regard to the epidemiology of multicystic dysplasia kidney, the incidence of MCDK is estimated to be 1 in every 4,000 live births, making it rare in terms of the general population.

Benign lymphoepithelial lesion is a type of benign enlargement of the parotid and/or lacrimal glands. This pathologic state is sometimes, but not always, associated with Sjögren's syndrome.

The cause of fibular hemimelia is unclear. Purportedly, there have been some incidents of genetic distribution in a family; however, this does not account for all cases. Maternal viral infections, embryonic trauma, teratogenic environmental exposures or vascular dysgenesis (failure of the embryo to form a satisfactory blood supply) between four and seven weeks gestation are considered possible causes.

In an experimental mouse model, change in the expression of a homeobox gene led to similar, but bilateral, fibular defects.

Bilateral Vestibulopathy results as the culmination of damage done to both inner ears. Bilateral Vestibulopathy causes problems in vision, hearing and motor coordination.

There is no known specific treatment for this condition. Management is supportive.

Vision improves in almost all cases. In rare cases, a patient may suffer permanent visual loss associated with lesions on their optic nerve.

Rarely, coexisting vasculitis may cause neurological complications. These occurrences can start with mild headaches that steadily worsen in pain and onset, and can include attacks of dysesthesia. This type of deterioration happens usually if the lesions involve the fovea.

Congenital onychodysplasia of the index fingers is defined by the presence of the condition at birth, either unilateral or bilateral index finger involvement, variable distortion of the nail or lunula, and polyonychia, micronychia, anonychia, hemionychogryphosis, or malalignment.

- The original paper was

- This condition is also called Iso-Kikuchi syndrome, since Iso was the first author who published it in a Japanese paper.

Hallermann–Streiff syndrome is a congenital disorder that affects growth, cranial development, hair growth and dental development. There are fewer than 200 people with the syndrome worldwide. An organization supporting people with the Hallermann–Streiff syndrome is the Germany-based "Schattenkinder e.V."

Treatment differs depending on the cause. Each cause has a different treatment, and may involve either medical treatment, surgery, or therapy. If serious damage has already been done, then the focus of treatment is upon avoidance of vestibular suppressants and ototoxins. It is recommended that you tell your physicians to avoid drugs that end in mycin ( Azithromycin, Erythromycin ) because of possible reactions which could lead to setbacks. Vestibular rehabilitation is important. Your physician will try to keep the administering of drugs to a minimum.

Microphthalmia–dermal aplasia–sclerocornea syndrome (also known as "MIDAS syndrome") is a condition characterized by linear skin lesions.

MLS is a rare X-linked dominant male-lethal disease characterized by unilateral or bilateral microphthalmia and linear skin defects in affected females, and in utero lethality for affected males. It can be associated with "HCCS", but mutations in the MCCS gene cause Microphthalmia with Linear Skin Defects Syndrome.

The most common cause of cortical blindness is ischemia (oxygen deprivation) to the occipital lobes caused by blockage to one or both of the posterior cerebral arteries. However, other conditions have also been known to cause acquired and transient cortical blindness, including:

- Bilateral lesions of the primary visual cortex

- Side effect of some anti-epilepsy drugs (AEDs)

- Creutzfeldt–Jakob disease, in association with a rapid onset of dementia

- Infection

- Head trauma to the occipital lobe of the brain

- Congenital abnormalities of the occipital lobe

- Eclampsia and, rarely, pre-eclampsia

- Hyperammonemia

The most common causes of congenital cortical blindness are:

- Traumatic brain injury (TBI) to the occipital lobe of the brain

- Congenital abnormalities of the occipital lobe

- Perinatal ischemia

- Encephalitis

- Meningitis

Raccoon eye/eyes (also known in the United Kingdom and Ireland as panda eyes) or periorbital ecchymosis is a sign of basal skull fracture or subgaleal hematoma, a craniotomy that ruptured the meninges, or (rarely) certain cancers. Bilateral hemorrhage occurs when damage at the time of a facial fracture tears the meninges and causes the venous sinuses to bleed into the arachnoid villi and the cranial sinuses. In layman's terms, blood from skull fracture seeps into the soft tissue around the eyes. Raccoon eyes may be accompanied by Battle's sign, an ecchymosis behind the ear. These signs may be the only sign of a skull fracture, as it may not show on an X-ray. They may not appear until up 2–3 days after the injury. It is recommended that the patient not blow their nose, cough vigorously, or strain to prevent further tearing of the meninges.

Raccoon eyes may be bilateral or unilateral. If bilateral, it is highly suggestive of basilar skull fracture, with a positive predictive value of 85%. They are most often associated with fractures of the anterior cranial fossa.

Raccoon eyes may also be a sign of disseminated neuroblastoma or of amyloidosis (multiple myeloma).

Depending on cause, raccoon eyes always require urgent consultation and management, that is surgical (facial fracture or post-craniotomy) or medical (neuroblastoma or amyloidosis).

Most optic nerve melanocytomas are small, black, and do not grow.

An optic nerve melanocytoma is a tumor made up of melanocytes and melanin. These tumors are typically a benign; they can grow, but rarely transform into a malignancy. Even so, local growth can affect adjacent tissues.

Patients with this syndrome are shorter than the average person and may not develop hair in many places, including in the facial, leg and pubic areas. Patients also have eye problems including reduced eye size, bilateral cataracts and glaucoma.

It can be associated with sleep apnea.

It can complicate intubation.