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.
Oculopharyngeal muscular dystrophy (OPMD) is a rare form of muscular dystrophy with symptoms generally starting when an individual is 40 to 50 years old. It can be autosomal dominant neuromuscular disease or autosomal recessive. The most common inheritance of OPMD is autosomal dominant, which means only one copy of the mutated gene needs to be present in each cell. Children of an affected parent have a 50% chance of inheriting the mutant gene.
Mulibrey nanism is a rare autosomal recessive congenital disorder. It causes severe growth failure along with abnormalities of the heart, muscle, liver, brain and eye. TRIM37 is responsible for various cellular functions including developmental patterning.
Hereditary inclusion body myopathies (HIBM) are a group of rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individuals, but all share similar structural features in the muscles.
Short-chain acyl-coenzyme A dehydrogenase deficiency (SCADD) is an autosomal recessive fatty acid oxidation disorder which affects enzymes required to break down a certain group of fats called short chain fatty acids.
Dermatopathia pigmentosa reticularis(DPR) is a rare, autosomal dominant congenital disorder that is a form of ectodermal dysplasia. Dermatopathia pigmentosa reticularis is composed of the triad of generalized reticulate hyperpigmentation, noncicatricial alopecia, and onychodystrophy. DPR is a non life-threatening disease that largely affects the skin, hair, and nails. It has also been identified as a keratin disorder. Historically, as of 1992, only 10 cases had been described in world literature; however, due to recent advances in genetic analysis, five additional families studied in 2006 have been added to the short list of confirmed cases.
17β-Hydroxysteroid dehydrogenase III deficiency is a rare autosomal recessive disorder of sexual development condition that is a cause of 46,XY disorder of sex development. The impaired testosterone biosynthesis by 17β-hydroxysteroid dehydrogenase III, presents as atypical genitalia in affected males.
Chronic mucocutaneous candidiasis is an immune disorder of T cells. It is characterized by chronic infections with Candida that are limited to mucosal surfaces, skin, and nails. It can also be associated with other types of infections, such as human papilloma virus. An association with chromosome 2 has been identified.
Ullrich congenital muscular dystrophy is a form of congenital muscular dystrophy. It is associated with variants of type VI collagen, it is commonly associated with muscle weakness and respiratory problems, though cardiac issues are not associated with this type of CMD. It is named after Otto Ullrich, who is also known for the Ullrich-Turner syndrome.
Brachydactyly-long thumb syndrome is a very rare genetic disorder which is characterized by symmetric brachydactyly of the fingers accompanied by an abnormally long thumb, hypomobility of the shoulder and metacarpo-phalangeal joints, and heart conduction defects. Small feet and hands, small shoulders accompanied with short clavicles, clinodactyly, pectus excavatum, mild limb shortening, cardiomegaly, and pulmonic stenosis murmur have also been reported. It was first discovered when D W Hollister et al. described 4 affected members belonging to a 3-generation family. No new cases have been reported since 1981. This disorder is inherited in an autosomal dominant manner.
Deafness-vitiligo-achalasia syndrome is an extremely rare genetic disorder characterized by congenital hearing loss, vitiligo, low height, muscle degeneration and achalasia. It was first discovered in 1971, when Rozycki et al., when they described two siblings of the opposite sex with the symptoms mentioned above. It is thought to be inherited in an autosomal recessive manner.
Acanthosis nigricans-muscle cramps-acral enlargement syndrome, also known as Acanthosis nigricans-insulin resistance-muscle cramps-acral enlargement syndrome is an extremely rare genetic disorder which is characterized by the appearance of acanthosis nigricans, insulin resistance, muscle cramps of severe intensity, and acral hypertrophy/enlargement. Only 2 cases have been reported in medical literature.
Spondylocamptodactyly, also known as Spondylocamptodactyly syndrome, is a very rare multi-systemic genetic disorder which is characterized by the presence of camptodactyly, flattened vertebrae and thoracic scoliosis of varying degrees. It has been described in 5 members of a 3-generation Mexican family, It is thought to be inherited in an either autosomal dominant or autosomal recessive with pseudodominance pattern.
Amaurosis congenita, cone-rod type, with congenital hypertrichosis is a very rare genetic disorder which is characterized by ocular anomalies and trichomegaly. It is inherited in an autosomal recessive manner. Only 2 cases have been described in medical literature.
Short-limb skeletal dysplasia with severe combined immunodeficiency is an extremely rare type of achondroplasia which is characterized by short stature, bowing of the long bones, and generalized metaphyseal abnormalities alongside signs of SCID such as recurrent severe infections, failure to thrive, chronic diarrhea, and a notable absence of T and B lymphocytes. It is inherited in an autosomal recessive manner. Around 11 cases have been described in medical literature.
Intellectual disability-spasticity-ectrodactyly syndrome, also known as Jancar syndrome, is a rare autosomal recessive genetic disorder which is characterized by severe intellectual disabilities, hereditary spastic paraplegia, and defects of the distal limbs, such as syndactyly, ectrodactyly, and clinodactyly. Only 3 families in England and Israel have been described in medical literature.
Wormian bone-multiple fractures-dentinogenesis imperfecta-skeletal dysplasia syndrome is a rare genetic bone disorder which is characterized by the presence of wormian bones in the skull, dentinogenesis imperfecta, recurrent bone fractures, hypertelorism, and eye puffiness. This disorder is unique from osteogenesis imperfecta because of the presence of cortical defects and the absence of defective collagen or osteopenia. It is not exactly known whether this condition is autosomal dominant or autosomal recessive.
Thoracic dysplasia-hydrocephalus syndrome is a rare autosomal recessive genetic disorder characterized by shortening of the ribs, narrowing of the chest, mild shortening of the limbs (rhizomelia), hydrocephalus, and variable developmental delays. It has been described in two siblings born to consanguineous Pakistani parents.
Odontoonychodermal dysplasia is a rare genetic disorder which is characterized by systemic abnormalities of the teeth, the nails of the fingers and toes, the skin, the hair cells, and the sweat glands. It is a type of syndromic ectodermal dysplasia.
