| Myhre syndrome | |
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| Other names | Facial dysmorphism-intellectual disability-short stature-hearing loss syndrome |
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| Myhre syndrome is inherited in an autosomal dominant manner [1] | |
| Specialty | Medical genetics |
Myhre syndrome is a rare genetic disorder inherited in an autosomal dominant fashion. It is caused by mutation in SMAD4 gene.
The clinical presentation is variable but includes[ citation needed ]
The facial abnormalities include:
The skeletal abnormalities include:
Congenital heart disease and undescended testes have also been reported in association with this syndrome.
Myhre syndrome is due to mutations in the SMAD4 gene. [2] This gene encodes a protein - transducer mediating transforming growth factor beta. Some researchers believe that the SMAD4 gene mutations that cause Myhre syndrome impair the ability of the SMAD4 protein to attach (bind) properly with the other proteins involved in the signaling pathway. Other studies have suggested that these mutations result in an abnormally stable SMAD4 protein that remains active in the cell longer. Changes in SMAD4 binding or availability may result in abnormal signaling in many cell types, which affects development of several body systems and leads to the signs and symptoms of Myhre syndrome. [3] [4]
The patients of this disease exhibit hypertrophic phenotype in their muscle tissues. Myostatin target genes are found to be downregulated while bone morphogenetic protein (BMP) target genes display both upregulated and downregulated genotypes. [4]
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This disorder was first reported in 1981. [5] It has many similarities to LAPS Syndrome and they both arise from the same mutations in the SMAD4 gene. It is believed that they are the same syndrome. [6]
Weissenbacher–Zweymuller syndrome (WZS), also called Pierre-Robin syndrome with fetal chondrodysplasia, is an autosomal recessive congenital disorder, linked to mutations in the COL11A2 gene, which codes for the α2 strand of collagen type XI. It is a collagenopathy, types II and XI disorder. The condition was first characterized in 1964 by G. Weissenbacher and Ernst Zweymüller.
Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored eyes, low-set ears, a short neck, and a small lower jaw. Heart problems may include pulmonary valve stenosis. The breast bone may either protrude or be sunken, while the spine may be abnormally curved. Intelligence in the syndrome is often normal. Complications of NS can include leukemia.
Treacher Collins syndrome (TCS) is a genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. The degree to which a person is affected, however, may vary from mild to severe. Complications may include breathing problems, problems seeing, cleft palate, and hearing loss. Those affected generally have normal intelligence.
Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby-cheeked resemblance to putti, often confused with cherubs, in Renaissance paintings.
Jackson–Weiss syndrome (JWS) is a genetic disorder characterized by foot abnormalities and the premature fusion of certain bones of the skull (craniosynostosis), which prevents further growth of the skull and affects the shape of the head and face. This genetic disorder can also sometimes cause intellectual disability and crossed eyes. It was characterized in 1976.
Simpson–Golabi–Behmel syndrome (SGBS), is a rare inherited congenital disorder that can cause craniofacial, skeletal, cardiac, and renal abnormalities. The syndrome is inherited in an X-linked recessive fashion, where males express the phenotype and females usually do not. Females that possess one copy of the mutation are considered to be carriers of the syndrome and may express varying degrees of the phenotype.
Larsen syndrome (LS) is a congenital disorder discovered in 1950 by Larsen and associates when they observed dislocation of the large joints and face anomalies in six of their patients. Patients with Larsen syndrome normally present with a variety of symptoms, including congenital anterior dislocation of the knees, dislocation of the hips and elbows, flattened facial appearance, prominent foreheads, and depressed nasal bridges. Larsen syndrome can also cause a variety of cardiovascular and orthopedic abnormalities. This rare disorder is caused by a genetic defect in the gene encoding filamin B, a cytoplasmic protein that is important in regulating the structure and activity of the cytoskeleton. The gene that influences the emergence of Larsen syndrome is found in chromosome region, 3p21.1-14.1, a region containing human type VII collagen gene. Larsen syndrome has recently been described as a mesenchyme disorder that affects the connective tissue of an individual. Autosomal dominant and recessive forms of the disorder have been reported, although most cases are autosomal dominant. Reports have found that in Western societies, Larsen syndrome can be found in one in every 100,000 births, but this is most likely an underestimate because the disorder is frequently unrecognized or misdiagnosed.
Osteochondrodysplasia is a general term for a disorder of the development (dysplasia) of bone ("osteo") and cartilage ("chondro"). Osteochondrodysplasias are rare diseases. About 1 in 5,000 babies are born with some type of skeletal dysplasia. Nonetheless, if taken collectively, genetic skeletal dysplasias or osteochondrodysplasias comprise a recognizable group of genetically determined disorders with generalized skeletal affection. Osteochondrodysplasias can result in marked functional limitation and even mortality.
Noonan syndrome with multiple lentigines (NSML) which is part of a group called Ras/MAPK pathway syndromes, is a rare autosomal dominant, multisystem disease caused by a mutation in the protein tyrosine phosphatase, non-receptor type 11 gene (PTPN11). The disease is a complex of features, mostly involving the skin, skeletal and cardiovascular systems, which may or may not be present in all patients. The nature of how the mutation causes each of the condition's symptoms is not well known; however, research is ongoing. It is a RASopathy.
Loeys–Dietz syndrome (LDS) is an autosomal dominant genetic connective tissue disorder. It has features similar to Marfan syndrome and Ehlers–Danlos syndrome. The disorder is marked by aneurysms in the aorta, often in children, and the aorta may also undergo sudden dissection in the weakened layers of the wall of the aorta. Aneurysms and dissections also can occur in arteries other than the aorta. Because aneurysms in children tend to rupture early, children are at greater risk for dying if the syndrome is not identified. Surgery to repair aortic aneurysms is essential for treatment.
Aarskog–Scott syndrome is a rare disease inherited as X-linked and characterized by short stature, facial abnormalities, skeletal and genital anomalies. This condition mainly affects males, although females may have mild features of the syndrome.
3C syndrome is a rare condition whose symptoms include heart defects, cerebellar hypoplasia, and cranial dysmorphism. It was first described in the medical literature in 1987 by Ritscher and Schinzel, for whom the disorder is sometimes named.
Zinc finger E-box-binding homeobox 2 is a protein that in humans is encoded by the ZEB2 gene. The ZEB2 protein is a transcription factor that plays a role in the transforming growth factor β (TGFβ) signaling pathways that are essential during early fetal development.
Keutel syndrome (KS) is a rare autosomal recessive genetic disorder characterized by abnormal diffuse cartilage calcification, hypoplasia of the mid-face, peripheral pulmonary stenosis, hearing loss, short distal phalanges (tips) of the fingers and mild mental retardation. Individuals with KS often present with peripheral pulmonary stenosis, brachytelephalangism, sloping forehead, midface hypoplasia, and receding chin. It is associated with abnormalities in the gene coding for matrix gla protein (MGP). Being an autosomal recessive disorder, it may be inherited from two unaffected, abnormal MGP-carrying parents. Thus, people who inherit two affected MGP genes will likely inherit KS.
3-M syndrome or 3M3 is a rare hereditary disorder characterized by severe growth retardation, facial dysmorphia, and skeletal abnormalities. The name 3-M is derived from the initials of the three researchers who first identified it: Miller, McKusick, and Malvaux and report their findings in the medical literature in 1972. Mutations in any one of the following three genes: CUL7, OBSL1, and CCDC8 are responsible for the occurrence of this disorder. It is inherited through an autosomal recessive pattern and considered very rare, so far less than 100 cases worldwide have been identified. Diagnosis is based on the presence of clinical features. Genetic testing can confirm the diagnosis and identify the specific gene involved. Treatment is aimed at addressing the growth and skeletal problems and may include surgical bone lengthening, adaptive aids, and physical therapy. An endocrinologist may assist with growth hormone replacement and appropriate evaluations during puberty.
A ciliopathy is any genetic disorder that affects the cellular cilia or the cilia anchoring structures, the basal bodies, or ciliary function. Primary cilia are important in guiding the process of development, so abnormal ciliary function while an embryo is developing can lead to a set of malformations that can occur regardless of the particular genetic problem. The similarity of the clinical features of these developmental disorders means that they form a recognizable cluster of syndromes, loosely attributed to abnormal ciliary function and hence called ciliopathies. Regardless of the actual genetic cause, it is clustering of a set of characteristic physiological features which define whether a syndrome is a ciliopathy.
Gerodermia osteodysplastica (GO), is a rare autosomal recessive connective tissue disorder included in the spectrum of cutis laxa syndromes.
Shwachman–Diamond syndrome (SDS), or Shwachman–Bodian–Diamond syndrome, is a rare congenital disorder characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, skeletal abnormalities and short stature. After cystic fibrosis (CF), it is the second most common cause of exocrine pancreatic insufficiency in children.
Donohue syndrome is an extremely rare and severe genetic disorder. Leprechaunism derives its name from the hallmark elvish features exhibited by the affected individuals. The disease is caused by a mutation in the INSR gene, which contains the genetic information for the formation of insulin receptors. As a result, affected individuals have either a decreased number of insulin receptors, or insulin receptor with greatly impaired functionality. The lack and impairment of insulin receptor functionality leads to an inability to regulate blood glucose levels through severe insulin resistance. This will ultimately lead to affected development of tissues and organs throughout the body. In addition to the physical abnormalities, leprechaunism is also characterized by endocrine system abnormalities that can lead to conditions such as hyperglycemia, hypoglycemia, hyperinsulemia, and the enlargement of certain sex organs such as the penis in males, and the clitoris in females.
Okamoto syndrome (OS), also known as Au–Kline syndrome (AKS), is a very rare autosomal dominant genetic condition characterised by congenital hydronephrosis, low muscle tone, heart defects, intellectual disability and characteristic facial features. Those affected often have neurological and skeletal abnormalities, as well as frequent urinary tract infections. Language and walking are usually delayed. Facial features include prominent, downturned ears, an open, downturned mouth and drooping eyelids (ptosis).
This article incorporates text from the United States National Library of Medicine (), which is in the public domain.
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