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 chromosomal 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.
Aniridia is the absence of the iris, a muscular structure that opens and closes the pupil to allow light into the eye. It is also responsible for eye color. Without it the central eye appears all black. It can be congenital, in which both eyes are usually involved, or caused by a penetrant injury. Isolated aniridia is a congenital disorder which is not limited to a defect in iris development, but is a panocular condition with macular and optic nerve hypoplasia, cataract, and corneal changes. Vision may be severely compromised and the disorder is frequently associated with a number of ocular complications: nystagmus, amblyopia, buphthalmos, and cataract. Aniridia in some individuals occurs as part of a syndrome, such as WAGR syndrome, or Gillespie syndrome.
Oculocerebrorenal syndrome is a rare X-linked recessive disorder characterized by congenital cataracts, hypotonia, intellectual disability, proximal tubular acidosis, aminoaciduria and low-molecular-weight proteinuria. Lowe syndrome can be considered a cause of Fanconi syndrome.
Rud syndrome is a poorly characterized disorder, probably of X-linked recessive inheritance, named after Einar Rud who described 2 patients with the case in 1927 and 1929. It was argued that all reported cases of Rud syndrome are genetically heterogeneous and significantly differ from the original case reports of Rud and that the designation Rud syndrome should be eliminated and that the patients with such diagnosis should be reassigned to other syndromes, such as Refsum disease and Sjögren-Larsson syndrome. Some consider Rud syndrome and Sjögren-Larsson syndrome the same entity and that Rud syndrome does not exist.
Heart-hand syndromes are a group of rare diseases that manifest with both heart and limb deformities.
Hand and foot deformity with flat facies is a rare congenital malformation syndrome, where an individual has features such as facial dysmorphism, short stature, and other malformations with the limbs.
Ectrodactyly with tibia aplasia/hypoplasia also known as cleft hand absent tibia is a very rare limb malformation syndrome which is characterized by ectrodactyly, and aplasia/hypoplasia of the tibia bone. Additional findings include cup-shaped ears, pre-postaxial polydactyly, and hypoplasia of the big toes, femur, patella, and ulnae bone. It is inherited as an autosomal dominant trait with reduced penetrance.
Van De Berghe Dequeker syndrome, also known as ulnar hypoplasia-split foot syndrome is a very rare congenital limb malformation syndrome which is characterized by severe ulnar hypoplasia, absence of the index to pinky finger in the hand, and split-foot. It was first discovered in 1978 by H van de Berghe et al. when he described four males of a two-generation family with a "lobster-claw foot" and an "ulnar defect". Minor severity of said ulnar defect and toe syndactyly in female members of the same family suggested that this disorder was transmitted in an X-linked recessive manner, although autosomal dominance with reduced penetrance wasn't excluded as an inheritance pattern.
Lowry-Wood syndrome, also simply known as LWS, is a very rare genetic disorder which is characterized by dysplasia of the epiphysis, low height/short stature, microcephaly, developmental delay, intellectual disabilities, and congenital nystagmus. Less common features include coxa vara and retinitis pigmentosa. Only 10 cases of this disorder have been described in medical literature. This disorder is associated with mutations in the RNU4ATAC gene, on chromosome 2q14.2
Multiple congenital anomalies-hypotonia-seizures syndrome is a rare multi-systemic genetic disorder which is characterized by developmental delay, seizures, hypotonia and heart, urinary, and gastrointestinal abnormalities.
Cataract-ataxia-deafness syndrome is a very rare genetic disorder which is characterized by mild intellectual disabilities, congenital cataracts, progressive hearing loss, ataxia, peripheral neuropathy, and short height. Only two cases have been reported in medical literature.
Waardenburg anophthalmia syndrome is a rare autosomal recessive genetic disorder which is characterized by either microphthalmia or anophthalmia, osseous synostosis, ectrodactylism, polydactylism, and syndactylism. So far, 29 cases from families in Brazil, Italy, Turkey, and Lebanon have been reported worldwide. This condition is caused by homozygous mutations in the SMOC1 gene, in chromosome 14.
Congenital muscular dystrophy-infantile cataract-hypogonadism syndrome is a very rare genetic disorder which is characterized by congenital muscular dystrophy, infantile-onset cataract, and hypogonadism. Males usually develop Klinefelter syndrome while females develop agenesis of the ovaries. It has been described in eight individuals of which seven came from Finnmark County, Norway. Inheritance pattern is thought to be autosomal recessive.
Curry-Jones syndrome is a rare genetic disorder which is characterized by brain, osseous, cutaneous, ocular, ans intestinal anomalies associated with congenital minor physical anomalies.
CAPOS syndrome is a rare genetic neurological disorder which is characterized by abnormalities of the feet, eyes and brain which affect their normal function. These symptoms occur episodically when a fever-related infection is present within the body.
Hypomyelination-congenital cataract syndrome is a rare autosomal recessive hereditary disorder that affects the brain's white matter and is characterized by congenital cataract, psychomotor development delays, and moderate intellectual disabilities. It is a type of leukoencephalopathy.
Splenogonadal fusion-limb defects-micrognathia syndrome, also known by its abbreviation, SGFLD syndrome, is a rare genetic disorder characterized by abnormal fusion of the spleen and the gonad alongside limb defects and orofacial anomalies. It is a type of syndromic dysostosis.
Holoprosencephaly-ectrodactyly-cleft lip/palate syndrome, also simply known as Hartsfield syndrome, is a rare genetic disorder characterized by the presence of variable holoprosencephaly, ectrodactyly, cleft lip and palate, alongside generalized ectodermal abnormalities. Additional findings include endocrine anomalies and developmental delays.
Heart-hand syndrome, Slovenian type is a rare autosomal dominant genetic disorder belonging to the heart-hand syndromes.
