Lhermitte–Duclos disease is a rare entity; approximately 222 cases of LDD have been reported in medical literature. Symptoms of the disease most commonly manifest in the third and fourth decades of life, although it may onset at any age. Men and women are equally affected, and there is not any apparent geographical pattern.

Worth syndrome is caused by a mutation in the LRP5 gene, located on human chromosome 11q13.4. The disorder is inherited in an autosomal dominant fashion. This indicates that the defective gene responsible for a disorder is located on an autosome (chromosome 11 is an autosome), and only one copy of the defective gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.

The prognosis is favorable in most patients with an isolated cutaneous abnormality. In the majority of cases, both the vivid red marking and the difference in circumference of the extremities regress spontaneously during the first year of life. It is theorized that this may be due to the normal maturation process, with thickening of the epidermis and dermis. Improvements for some patients can continue for up to 10 years, while in other cases, the marbled skin may persist for the patient's lifetime.

One study reported an improvement in lesions in 46% of patients within 3 years. If CMTC persists into adulthood, it can result in complaints due to paresthesia, increased sensitivity to cold and pain, and the formation of ulcers.

Few reports included long-term follow up of CMTC into adolescence and adulthood. While about 50% of patients seem to show definite improvement in the reticular vascular pattern, the exact incidence and cause of persistent cases are unknown.

Bazex–Dupré–Christol syndrome (also known as "Bazex syndrome", and "follicular atrophoderma and basal cell carcinomas") is a very rare condition inherited in an X-linked dominant fashion. Physical findings typically include follicular atrophoderma, multiple basal cell carcinomas, hypotrichosis, and hypohidrosis.

This condition should not be confused with the unrelated condition acrokeratosis paraneoplastica of Bazex, which may also be referred to Bazex syndrome.

Usually observed at birth or shortly thereafter in 94% of patients, in other reports, patients did not develop skin lesions until 3 months or even 2 years after birth. Females are typically affected more often than males (64%).

Naegeli–Franceschetti–Jadassohn syndrome (NFJS), also known as chromatophore nevus of Naegeli and Naegeli syndrome, is a rare autosomal dominant form of ectodermal dysplasia, characterized by reticular skin pigmentation, diminished function of the sweat glands, the absence of teeth and hyperkeratosis of the palms and soles. One of the most striking features is the absence of fingerprint lines on the fingers.

Naegeli syndrome is similar to dermatopathia pigmentosa reticularis, both of which are caused by a specific defect in the keratin 14 protein.

Because Cowden syndrome can be difficult to diagnose, the exact prevalence is unknown; however, it probably occurs in at least 1 in 200,000 people.

A 2010 review of 211 patients (21 from one center, and the remaining 190 from the external literature) studied the risks for cancer and Lhermitte-Duclos disease in Cowden syndrome patients.

The cumulative lifetime (age 70 years) risks were 89% for any cancer diagnosis (95% confidence interval (CI) = 80%,95%), breast cancer [female] 81% (CI = 66%,90%), LDD 32% (CI = 19%,49%), thyroid cancer 21% (CI = 14%,29%), endometrial cancer 19% (CI = 10%,32%) and renal cancer 15% (CI = 6%,32%). A previously unreported increased lifetime risk for colorectal cancer was identified (16%, CI = 8%,24%). Male CS patients had fewer cancers diagnosed than female patients and often had cancers not classically associated with CS.

Lhermitte–Duclos disease (LDD) (), also called dysplastic gangliocytoma of the cerebellum, is a rare, slowly growing tumor of the cerebellum, a gangliocytoma sometimes considered to be a hamartoma, characterized by diffuse hypertrophy of the granular layer of the cerebellum. It is often associated with Cowden syndrome. It was described by Jacques Jean Lhermitte and P. Duclos in 1920.

Worth syndrome, also known as benign form of Worth hyperostosis corticalis generalisata with torus platinus, autosomal dominant osteosclerosis, autosomal dominant endosteal hyperostosis or Worth disease, is a rare autosomal dominant congenital disorder that is caused by a mutation in the LRP5 gene. It is characterized by increased bone density and benign bony structures on the palate.

Most patients with hyper IgE syndrome are treated with long-term antibiotic therapy to prevent staphylococcal infections. Good skin care is also important in patients with hyper IgE syndrome. High-dose intravenous gamma-globulin has also been suggested for the treatment of severe eczema in patients with HIES and atopic dermatitis.

Syringomas can be found in association with other symptoms as part of a syndrome. Hailey-Hailey disease also known as familial benign chronic pemphigus is a blistering disease that can also include syringomas.

Several systemic syndromes have also been associated with syringoma including diabetes mellitus, down syndrome, Brooke-Spiegler, and Nicolau-Balus. Specifically, diabetes mellitus is strongly associated with clear cell syringoma consisting of nests of clear cells containing glycogen. It is thought that phosphorylase deficiency, resulting from elevated glucose levels seen in diabetes leads to an accumulation of glycogen in the skin and within the clear cells. The incidence of syringomas has been reported in up to 40 percent of people with Down syndrome and can be associated with a condition calcinosis cutis which requires prompt medical attention. Brooke-Spiegler syndrome is a rare autosomal dominant syndrome with cutaneous manifestations including syringomas and trichoepitheliomas. Nicolau-Balus is a rare autosomal dominant disorder consisting of atrophoderma vermiculata and syringomas.

Autosomal dominant porencephaly type I is rare and its prevalence and incidence are unknown. It affects males and females equally.

Blau Syndrome is an autosomal dominant genetic inflammatory disorder which affects the skin, eyes, and joints. It is caused by a mutation in the NOD2 (CARD15) gene. Symptoms usually begin before the age of 4, and the disease manifests as early onset cutaneous sarcoidosis, granulomatous arthritis, and uveitis.

Ramos-Arroyo syndrome is marked by corneal anesthesia, absence of the peripapillary choriocapillaris and retinal pigment epithelium, bilateral sensorineural hearing loss, unusual facial appearance, persistent ductus arteriosus, Hirschsprung disease, and moderate intellectual disability. It appears to be a distinct autosomal dominant syndrome with variable expressivity.

As of 2008 this syndrome has only been reported in five individuals within three generations of the same family; two young children, their mother, their uncle and their maternal grandmother. This most recent generation to be diagnosed with Ramos-Arroyo syndrome supports the hypothesis that this disease is a distinct autosomal

dominant disorder. If this syndrome could be identified in other families it may help to discriminate the gene responsible.

The cause of acrogeria is still not well determined. This disorder is thought to be inherited as an autosomal recessive genetic trait. However, the mode of genetic inheritance is not accurately known. It has been considered autosomal dominant and autosomal recessive, though most reported cases own a positive family background.

Mutations in the COL3A1 gene, located at chromosome 2q31–q32, have been reported in varied phenotypes, including acrogeria and vascular rupture in Ehlers-Danlos' syndrome (more especially type IV).

In the fibroblast culture, a reduction of RNA messenger cells in collagen types I and II was found, as well as reduced life expectancy of the fibroblasts most prematurely showing morphological alterations typical of aging.

This seems perfectly compatible with the patients' aged phenotype.

Acrogeria is extremely rare, with only about 40 cases having been reported in the medical literature, since 1941.

An extremely rare disease of which only a few isolated cases are known.

NFJS is caused by mutations in the keratin 14 (KRT14) gene, located on chromosome 17q12-21. The disorder is inherited in an autosomal dominant manner, which means that the defective gene responsible for a disorder is located on an autosome (chromosome 17 is an autosome), and only one copy of the defective gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.

Dyschromatosis universalis hereditaria is a rare genodermatosis characterized by reticulate hyper- and hypo- pigmentated macules in a generalized distribution.

Both autosomal dominant and recessive inheritance have been reported with the disorder.

In terms of treatment/management one should observe what signs or symptoms are present and therefore treat those as there is no other current guideline. The affected individual should be monitored for cancer of:

- Thyroid

- Breast

- Renal

Medical conditions include frequent ear infection, hearing loss, hypotonia, developmental problems, respiratory problems, eating difficulties, light sensitivity, and esophageal reflux.

Data on fertility and the development of secondary sex characteristics is relatively sparse. It has been reported that both male and female patients have had children. Males who have reproduced have all had the autosomal dominant form of the disorder; the fertility of those with the recessive variant is unknown.

Researchers have also reported abnormalities in the renal tract of affected patients. Hydronephrosis is a relatively common condition, and researchers have theorized that this may lead to urinary tract infections. In addition, a number of patients have suffered from cystic dysplasia of the kidney.

A number of other conditions are often associated with Robinow syndrome. About 15% of reported patients suffer from congenital heart defects. Though there is no clear pattern, the most common conditions include pulmonary stenosis and atresia. In addition, though intelligence is generally normal, around 15% of patients show developmental delays.

Erythrokeratodermia variabilis (also known as "erythrokeratodermia figurata variabilis", "keratosis extremitatum progrediens", "keratosis palmoplantaris transgrediens et progrediens", "Mendes da Costa syndrome", "Mendes da Costa type erythrokeratodermia", and "progressive symmetric erythrokeratoderma") is a rare autosomal dominant disorder that usually presents at birth or during the first year of life. To date, it is thought to be caused by mutations in genes encoding for connexin channels proteins in the epidermis, leading to the misregulation of homeostasis in keratinocytes.

One type is characterized by generalized, persistent, brown hyperkeratosis with accentuated skin markings, while a second type is localized, with involvement that is limited in extent and characterized by sharply demarcated, hyperkeratotic plaques.

It can be associated with GJB3 and GJB4.

It was characterized in 1925.

It is characterized by recurrent "cold" staphylococcal infections, unusual eczema-like skin rashes, severe lung infections that result in pneumatoceles (balloon-like lesions that may be filled with air or pus or scar tissue) and very high concentrations of the serum antibody IgE. Inheritance can be autosomal dominant or autosomal recessive. Many patients with autosomal dominant STAT3 hyper-IgE syndrome have characteristic facial and dental abnormalities, fail to lose their primary teeth, and have two sets of teeth simultaneously.

Zimmermann–Laband syndrome (ZLS), also known as Laband–Zimmermann syndrome, and Laband's syndrome, is an extremely rare autosomal dominant congenital disorder.

Cutis laxa (also known as chalazoderma, dermatochalasia, dermatolysis, dermatomegaly, generalized elastolysis, generalized elastorrhexis, or pachydermatocele) is a group of rare connective tissue disorders in which the skin becomes inelastic and hangs loosely in folds.