A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development, or it can be inherited from two parents who are carriers of a faulty gene or from a parent with the disorder. When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y chromosome or mitochondrial DNA.
Tietz syndrome, also called Tietz albinism-deafness syndrome or albinism and deafness of Tietz, is an autosomal dominant congenital disorder characterized by deafness and leucism. It is caused by a mutation in the microphthalmia-associated transcription factor (MITF) gene. Tietz syndrome was first described in 1963 by Walter Tietz (1927–2003) a German Physician working in California.
Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13. The extra genetic material disrupts normal development, causing multiple and complex organ defects.
Hypopigmentation is characterized specifically as an area of skin becoming lighter than the baseline skin color, but not completely devoid of pigment. This is not to be confused with depigmentation, which is characterized as the absence of all pigment. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin. Some common genetic causes include mutations in the tyrosinase gene or OCA2 gene. As melanin pigments tend to be in the skin, eye, and hair, these are the commonly affected areas in those with hypopigmentation.
Ectodermal dysplasia (ED) is a group of genetic syndromes all deriving from abnormalities of the ectodermal structures. More than 150 different syndromes have been identified.
Sturge–Weber syndrome, sometimes referred to as encephalotrigeminal angiomatosis, is a rare congenital neurological and skin disorder. It is one of the phakomatoses and is often associated with port-wine stains of the face, glaucoma, seizures, intellectual disability, and ipsilateral leptomeningeal angioma. Sturge–Weber syndrome can be classified into three different types. Type 1 includes facial and leptomeningeal angiomas as well as the possibility of glaucoma or choroidal lesions. Normally, only one side of the brain is affected. This type is the most common. Type 2 involvement includes a facial angioma with a possibility of glaucoma developing. There is no evidence of brain involvement. Symptoms can show at any time beyond the initial diagnosis of the facial angioma. The symptoms can include glaucoma, cerebral blood flow abnormalities and headaches. More research is needed on this type of Sturge–Weber syndrome. Type 3 has leptomeningeal angioma involvement exclusively. The facial angioma is absent and glaucoma rarely occurs. This type is only diagnosed via brain scan.
Albinism-black lock-cell migration disorder is the initialism for the following terms and concepts that describe a condition affecting a person's physical appearance and physiology: (1) A – albinism, (2) B – black lock of hair, (3) C – cell migration disorder of the neurocytes of the gut, and (4) D – sensorineural deafness. The syndrome is caused by mutation in the endothelin B receptor gene (EDNRB).
Heřmanský–Pudlák syndrome is an extremely rare autosomal recessive disorder which results in oculocutaneous albinism, bleeding problems due to a platelet abnormality, and storage of an abnormal fat-protein compound. It is thought to affect around 1 in 500,000 people worldwide, with a significantly higher occurrence in Puerto Ricans, with a prevalence of 1 in 1800. Many of the clinical research studies on the disease have been conducted in Puerto Rico.
Nevoid basal-cell carcinoma syndrome (NBCCS) is a rare inherited medical condition involving defects within multiple body systems such as the skin, nervous system, eyes, endocrine system, and bones. People with NBCCS are prone to developing various cancers, including a common and usually non-life-threatening form of non-melanoma skin cancer called basal-cell carcinomas (BCCs). Only about 10% of people with the condition do not develop BCCs; the vast majority of patients develop numerous BCCs.
Greig cephalopolysyndactyly syndrome is a disorder that affects development of the limbs, head, and face. The features of this syndrome are highly variable, ranging from very mild to severe. People with this condition typically have one or more extra fingers or toes (polydactyly) or an abnormally wide thumb or big toe (hallux).
Ectrodactyly–ectodermal dysplasia–cleft syndrome, or EEC, and also referred to as EEC syndrome and split hand–split foot–ectodermal dysplasia–cleft syndrome is a rare form of ectodermal dysplasia, an autosomal dominant disorder inherited as a genetic trait. EEC is characterized by the triad of ectrodactyly, ectodermal dysplasia, and facial clefts. Other features noted in association with EEC include vesicoureteral reflux, recurrent urinary tract infections, obstruction of the nasolacrimal duct, decreased pigmentation of the hair and skin, missing or abnormal teeth, enamel hypoplasia, absent punctae in the lower eyelids, photophobia, occasional cognitive impairment and kidney anomalies, and conductive hearing loss.
Neonatal-onset multisystem inflammatory disease is a rare genetic periodic fever syndrome which causes uncontrolled inflammation in multiple parts of the body starting in the newborn period. Symptoms include skin rashes, severe arthritis, and chronic meningitis leading to neurologic damage. It is one of the cryopyrin-associated periodic syndromes.
NF-kappa-B essential modulator (NEMO) also known as inhibitor of nuclear factor kappa-B kinase subunit gamma (IKK-γ) is a protein that in humans is encoded by the IKBKG gene. NEMO is a subunit of the IκB kinase complex that activates NF-κB. The human gene for IKBKG is located on the chromosome band Xq28. Multiple transcript variants encoding different isoforms have been found for this gene.
Oculocutaneous albinism type I or type 1A is form of the autosomal recessive condition oculocutaneous albinism that is caused by a dysfunction in the gene for tyrosinase.
Focal dermal hypoplasia is a form of ectodermal dysplasia. It is a multisystem disorder characterized primarily by skin manifestations to the atrophic and hypoplastic areas of skin which are present at birth. These defects manifest as yellow-pink bumps on the skin and pigmentation changes. The disorder is also associated with shortness of stature and some evidence suggests that it can cause epilepsy.
Incontinentia pigmenti achromians is a cutaneous condition characterized by various patterns of bilateral or unilateral hypopigmentation following the lines of Blaschko. Though the consistency of the skin findings have led to the term "hypomelanosis of Ito", it actually refers to a group of disorders with various genetic causes including polyploidies and aneuploidies. Based upon the specifics of the genetic defect, the skin findings can be accompanied by a great range of systemic findings. These include central nervous system, ocular, and musculoskeletal defects. Nonetheless, the vast majority of cases are limited to the skin. As opposed to incontinentia pigmenti, hypomelanosis of Ito affects both genders equally. This disorder was first described by Japanese dermatologist Minoru Ito in 1952.
Gillespie syndrome, also called aniridia, cerebellar ataxia and mental deficiency, is a rare genetic disorder. The disorder is characterized by partial aniridia, ataxia, and, in most cases, intellectual disability. It is heterogeneous, inherited in either an autosomal dominant or autosomal recessive manner. Gillespie syndrome was first described by American ophthalmologist Fredrick Gillespie in 1965.
Setleis syndrome is a very rare genetic condition characterized by facial skin abnormalities and double upper eyelashes and missing lower eyelashes. It belongs to a group of diseases known as ectodermal dysplasias. Ectodermal dysplasias typically affect the hair, teeth, nails, and/or skin. Setleis syndrome is characterized by distinctive abnormalities of the facial area that may be apparent at birth (congenital). Most affected infants have multiple, scar-like, circular depressions on both temples (bitemporal). These marks closely resemble those made when forceps are used to assist delivery. The range and severity of symptoms may vary from case to case.
Otodental syndrome, also known as otodental dysplasia, is an exceptionally rare disease that is distinguished by a specific phenotype known as globodontia, that in rare cases can be associated with eye coloboma and high frequency hearing loss. Globodontia is an abnormal condition that can occur in both the primary and secondary dentition, except for the incisors which are normal in shape and size. This is demonstrated by significant enlargement of the canine and molar teeth. The premolars are either reduced in size or are absent. In some cases, the defects affecting the teeth, eye and ear can be either individual or combined. When these conditions are combined with eye coloboma, the condition is also known as oculo-otodental syndrome. The first known case of otodental syndrome was found in Hungary in a mother and her son by Denes and Csiba in 1969. Prevalence is less than 1 out of every 1 million individuals. The cause of otodental syndrome is considered to be genetic. It is an autosomal dominant inheritance and is variable in its expressivity. Haploinsufficiency in the fibroblast growth factor 3 (FGF3) gene (11q13) has been reported in patients with otodental syndrome and is thought to cause the phenotype. Both males and females are equally affected. Individuals diagnosed with otodental syndrome can be of any age; age is not a relevant factor. Currently there are no specific genetic treatments for otodental syndrome. Dental and orthodontic management are the recommended course of action.
Nuclear factor-kappa B Essential Modulator (NEMO) deficiency syndrome is a rare type of primary immunodeficiency disease that has a highly variable set of symptoms and prognoses. It mainly affects the skin and immune system but has the potential to affect all parts of the body, including the lungs, urinary tract and gastrointestinal tract. It is a monogenetic disease caused by mutation in the IKBKG gene. NEMO is the modulator protein in the IKK inhibitor complex that, when activated, phosphorylates the inhibitor of the NF-κB transcription factors allowing for the translocation of transcription factors into the nucleus.
