TaoMedAI/RareMedData huggingface dataset:
Meacham syndrome (ORPHA:3097)
Meacham syndrome is a multiple malformation syndrome characterized by congenital diaphragmatic abnormalities, genital defects and cardiac malformations.
Epidemiology
Less than 15 patients have been reported worldwide.
Clinical description
Ambiguous or female external genitalia are present in individuals with 46,XY karyotype. The genital abnormalities are variable and may include a true double vagina or septate vagina, absent uterus, abnormal male gonads in the presence of normal external female genitalia or male pseudohermaphroditism with abnormal internal female genitalia. Complex cyanotic congenital heart defects, (hypoplastic right lungs, anomalous pulmonary venous return and abnormalities of the diaphragm) are frequent. One patient with rhabdomyomatous dysplasia of the lungs has been reported.
Etiology
Mutations in the WT1 gene have been identified in some patients with Meacham syndrome. Mutations in the same gene have previously been detected in patients with Denys-Drash syndrome (see this term).
Diagnostic methods
Diagnosis is based on the clinical findings. The occurrence of a true double vagina should lead the clinician to careful pulmonary and cardiac evaluation.
Differential diagnosis
The main differential diagnosis comprises Denys-Drash syndrome, an allelic disorder with overlapping clinical features. Beckwith-Wiedemann, Simpson-Golabi-Behmel and Perlman syndromes should also be considered (see these terms).
Management and treatment
Management is supportive.
Prognosis
All patients reported to date died in early childhood.

                            Last update: 
                            December 2008
Meconium aspiration syndrome (ORPHA:70588)
Meconium aspiration syndrome is a pulmonary complication appearing in newborns with a meconium-stained amniotic fluid. Aspirated meconium can interfere with normal breathing by several mechanisms including airway obstruction, chemical irritation, infection and surfactant inactivation and induces more or less severe signs of respiratory distress at birth.
Medial condensing osteitis of the clavicle (ORPHA:57196)
A rare bone disease characterized by benign, usually unilateral, sclerosis of the inferomedial third of the clavicle. Patients present with localized swelling and persistent pain. Typical radiographic findings are expansion of the medial end of the clavicle with increased radio-density and signs of bone remodeling.
Median cleft lip/mandible (ORPHA:2006)
A rare median facial cleft characterized by median cleft of the lower lip (ranging in extent from a notch in the vermilion to a complete cleft involving the tongue, lower lip, and chin, and extending to the cervical region), median cleft of the mandible (ranging from notching to a complete cleft), and anomaly of the tongue including bifid tongue and tongue tie. Associated features in severe cases may include absent hyoid, thyroid cartilage, and manubrium sterni, as well as atrophic neck muscles.
Median cleft of the upper lip and maxilla (ORPHA:141239)
A rare median facial cleft characterized by a midline vertical cleft through the upper lip and premaxillary bone, which is highly variable in its extent and may also involve the nasal septum and central nervous system. Depending on the severity of the defect, associated manifestations include atrophy of midline structures, hypo-/hypertelorism, monophthalmia, proboscis, nasal deformity, median alveolar cleft, and short upper frenulum.
Median nodule of the upper lip (ORPHA:2699)
A rare familial facial anomaly characterized by a nodule beneath the vermilion border of the upper lip that tapered into the frenulum. The lesion is soft, easily compressible and asymptomatic. It can be wide (up to 8 mm) or flat and less prominent. Regression of the nodule by age has been reported. There have been no further descriptions in the literature since 1994.
Medich giant platelet syndrome (ORPHA:370127)
Medich giant platelet syndrome (MGPS) is a platelet granule disorder characterized by thrombocytopenia with giant platelets resulting in easy bleeding.
MEDNIK syndrome (ORPHA:171851)
A rare disorder of copper metabolism characterized by intellectual deficit, enteropathy, sensorineural hearing loss, peripheral neuropathy, lamellar and erythrodermic ichthyosis, and keratodermia.
Medullary thyroid carcinoma (ORPHA:1332)
Medullary thyroid carcinoma (MTC) is developed from thyroid C cells that secrete calcitonin (CT).
Epidemiology
MTC represents 5-10% of thyroid cancers with a 1-2% incidence in nodular thyroid diseases. Estimated prevalence in the general population is 1/14,300.
Diagnostic methods
Diagnosis is usually made in the presence of a solitary nodule often associated with nodal metastasis and confirmed by a high basal CT level which represents its biological marker. MTC may present as a sporadic form, and in about 30% of cases, as a familial form as a part of multiple endocrine neoplasia (see this term); a dominant inherited disease related to germline mutation of the protooncogene RET. Both biological (CT) and genetic (RET) markers allows optimal diagnosis and treatment of MTC; the former allowing screening and early diagnosis of MTC by routine CT measurements in nodular thyroid diseases that require adequate and complete surgery required to be performed. The former leads to the diagnosis of familial MTC and to the identification of at-risk subjects on whom early or prophylactic surgery may be performed.
Management and treatment
Treatment of MTC is based on complete surgical resection, including total thyroidectomy along with central and laterocervical nodal dissection. For locally advanced or metastatic MTC, complete cervical surgery is required and needs to be combined with other systemic treatments; as chemotherapy is not very efficient, radioimmunotherapy and RET target gene therapy (mainly tyrosine kinase inhibitors) appear as possible valuable therapeutic options for the future.
Prognosis
Ten-year survival is about 80% when patients are not surgically cured and reaches 95% when the biological marker CT is normalized after surgery.

                            Last update: 
                            November 2007


                            - Expert reviewer(s): 
                            Pr Bernard CONTE-DEVOLX  - Pr Patricia NICCOLI
Medulloblastoma with extensive nodularity (ORPHA:251858)
Medulloblastoma with extensive nodularity (MBEN) is a histological variant of medulloblastoma (see this term), an embryonic malignancy, most often located in the inferior medullary velum and then growing into the fourth ventricle, and presenting in infants and young children with symptoms of increased intracranial pressure such as headache, listlessness, vomiting, diplopia and papilledema. It is often associated with Gorlin syndrome (see this term) and has a relatively good prognosis.
Meesmann corneal dystrophy (ORPHA:98954)
Meesmann corneal dystrophy (MECD) is a rare form of superficial corneal dystrophy characterized by distinct tiny bubble-like, round-to-oval punctate bilateral opacities in the central corneal epithelium, and to a lesser extent in the peripheral cornea, with little impact on vision.
Epidemiology
Prevalence of this form of corneal dystrophy is not known as a registry of affected cases does not exist. Numerous cases have been reported from Denmark, Germany, Japan, USA, Saudi Arabia and Poland.
Clinical description
Lesions develop during infancy. MECD often remains asymptomatic until middle age, when intermittent, mild ocular irritation, photophobia, transient blurred vision, and irregular astigmatism develop. The condition persists throughout life. In severe cases, subepithelial scarring produces a slight grayish central corneal opacification. Corneal sensitivity is normal.
Etiology
Meesmann corneal dystrophy is caused by a mutation in one of a pair of genes, KRT3 (12q13.13) or KRT12 (17q11-q1) that encode the two units of cytokeratin in the corneal epithelium. Stocker-Holt corneal dystrophy is a variant of MECD caused by a p. Arg19Leu amino acid change in cytokeratin 12.
Diagnostic methods
Light microscopy reveals intraepithelial cysts and the epithelium may be thickened and disorganized. Histopathologically, MECD is characterized by intraepithelial cysts at different levels in the corneal epithelium, which is irregular in thickness.
Differential diagnosis
Suspected cases of MECD should be differentiated from other disorders of the corneal epithelium, such as vapor spray keratitis, mild epithelial edema and the bleb pattern of epithelial basement membrane dystrophy. MECD and Lisch epithelial corneal dystrophy (LECD, see this term) have clinical similarities but are easily distinguished from one another by the different modes of inheritance, i.e. autosomal dominant versus X-linked recessive.
Genetic counseling
MECD has an autosomal dominant pattern of inheritance.
Management and treatment
Removal of the abnormal corneal epithelium has been used to treat MECD, but this approach is not curative as the dystrophy recurs in the regenerated epithelium.

                            Last update: 
                            May 2012


                            - Expert reviewer(s): 
                            Dr Gordon KLINTWORTH
Mega-cisterna magna (ORPHA:97252)
A rare, non-syndromic, posterior fossa malformation characterized by a cisterna magna that measures above 15 mm in length, 5 mm in height and 20 mm in width (or greater than 10 mm in fetuses) associated with a normal cerebellar vermis and absence of hydrocephalus. The majority of patients are asymptomatic; however, variable neurodevelopmental outcomes, including delayed speech and language development, motor development delay, visiospatial perception difficulties, and attention problems, has been observed in some patients.
Megaconial congenital muscular dystrophy (ORPHA:280671)
A rare, genetic, skeletal muscle disease characterized by an early-onset hypotonia, muscle weakness, global developmental delay with intellectual disability, and cardiomyopathy. Congenital structural heart defects and ichthyosiform cutaneous lesions have also been associated. Muscle biopsy shows characteristic enlarged mitochondria located at the periphery of muscle fibers.
Megacystis-megaureter syndrome (ORPHA:238637)
Megacystic-megaureter syndrome is an urinary tract malformation characterized by the presence of a massive primary non-obstructive vesicoureteral reflux and a large capacity, smooth, thin walled bladder due to the continual recycling of refluxed urine. Recurrent urinary infections are commonly associated with this condition.
Megakaryoblastic acute myeloid leukemia with t(1;22)(p13;q13) (ORPHA:402023)
Megakaryoblastic acute myeloid leukemia with t(1;22)(p13;q13) is a rare subtype of acute myeloid leukemia with recurrent cytogenetic abnormalities characterized by clonal proliferation of myeloid blasts with predominantly megakaryoblastic differentiation in the bone marrow and blood, often with extensive infiltration of the abdominal organs. It occurs typically in infants and usually presents with hepatosplenomegaly, anemia, thrombocytopenia and nonspecific symptoms related to ineffective hematopoiesis (fatigue, bleeding and bruising, recurrent infections). Myelofibrosis and fibrosis of other infiltrated organs is also characteristic of this disease.
Megalencephalic leukoencephalopathy with subcortical cysts (ORPHA:2478)
A form of leukodystrophy that is characterized by infantile-onset macrocephaly, often with mild neurologic signs at presentation (such as mild motor delay), which worsen with time, leading to poor ambulation, falls, ataxia, spasticity, increasing seizures and cognitive decline. Brain magnetic resonance imaging reveals diffusely abnormal and mildly swollen white matter as well as subcortical cysts in the anterior temporal and frontoparietal regions.
Megalencephaly-polymicrogyria-postaxial polydactyly-hydrocephalus syndrome (ORPHA:83473)
A rare syndrome with a central nervous system malformation as a major feature characterized by macrocephaly, megalencephaly, bilateral perisylvian polymicrogyria, variable degrees of ventriculomegaly/hydrocephalus, developmental delay and intellectual disability, oromotor dysfunction, hypotonia, seizures, and dysmorphic facial features (such as frontal bossing, low-set ears, a flat nasal bridge, and high-arched palate). Postaxial polydactyly of one or more extremities is also common.
Megalencephaly-severe kyphoscoliosis-overgrowth syndrome (ORPHA:457359)
A rare genetic multiple congenital anomalies/dysmorphic syndrome characterized by overgrowth and macrocephaly with megalencephaly apparent at birth, global developmental delay, intellectual disability, and dysmorphic facial features (including frontal bossing, long face, sparse eyebrows, hypertelorism, downslanting palpebral fissures, and prognathism). Patients may exhibit tall stature with dolichostenomelia, arachnodactyly, kyphoscoliosis, and joint laxity, as well as neurologic manifestations, such as hypotonia, gait ataxia, or seizures. Brain imaging may show increased white matter volume, thick corpus callosum, or small cerebellum.
Megalencephaly (ORPHA:2477)
A rare central nervous system malformation characterized by an abnormally large brain, accompanied by abnormal head circumference measurements evident at birth or developing over the first years of life. The condition can be unilateral or bilateral and affects males more often than females. There is no typical pattern of symptoms, but mental retardation, seizures, and other neurologic abnormalities have been reported.
Megalocornea-intellectual disability syndrome (ORPHA:2479)
Megalocornea-intellectual disability syndrome is a rare intellectual disability syndrome most commonly characterized by megalocornea, congenital hypotonia, varying degrees of intellectual disability, psychomotor/developmental delay, seizures, and mild facial dysmorphism (including round face, frontal bossing, antimongoloid slant of the eyes, epicanthal folds, large low set ears, broad nasal base, anteverted nostrils, and long upper lip). Interfamilial and intrafamilial clinical variability has been reported.
MEGDEL syndrome (ORPHA:352328)
MEGDEL syndrome is a rare, genetic, neurometabolic disorder characterized by neonatal hypoglycemia, features of sepsis that are not linked to infection, development of feeding problems, failure to thrive, transient liver dysfunction, and truncal hypotonia followed by dystonia and spasticity which results in psychomotor development arrest and/or regression. Progressive sensorineural deafness, intellectual disability and absent speech are also associated. Laboratory tests demonstrate 3-methylglutaconic aciduria and temporary elevated serum lactate and transaminases.
Meige disease (ORPHA:90186)
Meige disease is a frequent form of late-onset, primary lymphedema characterized by lower limb lymphedema typically developing during puberty.
Meigs syndrome (ORPHA:314451)
Meigs syndrome is a rare neoplastic disease characterized by the clinical triad of benign ovarian tumor (typically, ovarian fibroma or fibroma-like tumor), hydrothorax and ascites, which resolve after tumor resection. Patients usually present with dyspnea, pelvic mass with or without a tender, distended abdomen and/or weight loss.
Melanoma and neural system tumor syndrome (ORPHA:252206)
Melanoma and neural system tumor syndrome is an extremely rare tumor association characterized by dual predisposition to melanoma and neural system tumors (typically astrocytoma; see this term).
Epidemiology
Prevalence and incidence rates are not known. Fewer than 20 affected families have been reported to date. Cases have been reported from France, Italy, the UK and the USA.
Clinical description
In reported families, affected individuals had cutaneous melanoma in association with dysplastic nevi, astrocytoma, benign or malignant peripheral nerve sheath tumor, neurofibroma, medulloblastoma, glioblastoma multiforme, ependymoma, glioma, and meningioma (see these terms). In some cases, melanoma was described first followed by nervous system tumors, and in other cases, melanoma was a secondary cancer.
Etiology
The etiology of this tumor association is unknown. Genetic mutations or germline deletions are thought to underlie this cancer susceptibility syndrome.
Genetic counseling
Male-to-male transmission was reported in one family but inheritance patterns are not clearly characterized. The increased risk appears to be found in both first- and second-degree relatives.

                            Last update: 
                            March 2015


                            - Expert reviewer(s): 
                            Dr Monica RODOLFO
Melanoma of soft tissue (ORPHA:97338)
A rare soft tissue tumor characterized by a slowly growing mass typically involving tendons and aponeuroses of the extremities, composed of polygonal or spindle-shaped cells with melanocytic differentiation. The tumor typically affects young adults, who often present with pain or tenderness at the tumor site. Prognosis is poor with high recurrence rates and frequent metastasis, especially to lymph nodes, lung, and bones.
Melhem-Fahl syndrome (ORPHA:2482)
Melhem-Fahl syndrome was described in two siblings born to consanguineous parents in 1985 and was characterized by the presence of 15 dorsal vertebrae and rib pairs. No other cases have been documented since the initial report.
Melioidosis (ORPHA:31202)
A tropical infectious disease caused by the Gram-negative bacterium Burkholderia pseudomallei, which is present in soil and water in tropical countries. Melioidosis can present itself in many ways, including pneumonia, sepsis and abscess formation.
Epidemiology
Melioidosis is present throughout the tropics and highly endemic in (Southeast) Asia and Australia. The disease is increasingly reported in African and South American countries. Melioidosis has a male predominance and may occur in any age group, but is more frequent between 40 and 60 years of age.
Clinical description
The incubation period varies from days to months or years. Melioidosis has a spectrum of clinical manifestations ranging from local skin infection to pneumonia, sepsis and abscess formation. Less frequent manifestations include involvement of the central nervous system or the musculoskeletal apparatus. Melioidosis presents as an acute disease in the majority of cases, characterized by respiratory infections and septicemia. It can also present as a chronic infection characterized by subacute tuberculosis-like lesions or non-healing skin infections.
Etiology
Melioidosis is caused by the Gram-negative bacterium Burkholderia pseudomallei, which is present in soil and water in tropical countries. Rice fields are associated with the presence of B. pseudomallei. The bacterium can enter the body via inoculation, inhalation or ingestion. Risk factors include diabetes, chronic kidney, lung and liver disease and alcohol abuse.
Diagnostic methods
The gold standard for diagnosis is culture and identification of B. pseudomallei from patient samples (of blood, sputum, urine and wounds). Ideally, suspected isolates are confirmed using PCR or sequencing methods. Currently available antibody tests, such as the indirect hemagglutination assay, are less reliable, but can provide information about exposure to the bacterium. Imaging is important to assess the extent of disease.
Differential diagnosis
Differential diagnosis includes tuberculosis, pneumonia, and other infectious diseases such as plague, typhoid fever and syphilis.
Management and treatment
Patients are treated with an initial intensive phase of antibiotics with ceftazidime or carbapenem (i.e. meropenem or imipenem) followed by a longer eradication phase with preferably cotrimoxazole.
Prognosis
The mortality varies and is dependent on available diagnostics and therapeutic options. The reported mortality is around 40% in low- and middle-income countries, while in Australia the mortality is almost 5%. Early recognition and adequate treatment are key. Relapses can occur.

                            Last update: 
                            July 2023


                            - Expert reviewer(s): 
                             J. [Jelmer] SAVELKOEL  - Pr W.J. [Joost] WIERSINGA
Melkersson-Rosenthal syndrome (ORPHA:2483)
A rare orofacial granulomatosis characterized by the triad of recurrent or persistent orofacial edema (facial and lip edemas), fissured tongue, and relapsing, unilateral or bilateral peripheral facial nerve paralysis. Most cases present with partial symptoms. Typical age of onset is in childhood or adolescence. Histological examination shows non-caseating epithelioid cell granulomas and lymphedema.
Melnick-Needles syndrome (ORPHA:2484)
Melnick-Needles syndrome (MNS) belongs to the otopalatodigital syndrome spectrum disorder and is associated with a short stature, facial dysmorphism, osseous abnormalities involving the majority of the axial and appendicular skeleton resulting in impaired speech and masticatory problems.
Epidemiology
To date, less than 70 cases with MNS have been documented. MNS is a disorder essentially limited to females as it is lethal in males. Survivorship in males is possible due to mosaicism.
Clinical description
MNS is a congenital disorder characterized by a short stature, facial dysmorphism (small facies with prominent forehead, full cheeks, retrognathia, marked micrognathia), impaired speech, masticatory problems, and bowing of the arms and lower legs. Eye and ear abnormalities include bilateral exophthalmus, strabismus, blue sclera, conductive deafness and large pinna. Kyphoscoliosis is common. Mitral and tricuspid valve prolapse, bowel malrotation, hydronephrosis, and joint subluxation may be observed. Severe mandibular hypoplasia can cause upper airway restriction, obstructive sleep apnea syndrome and pneumonia and occasionally respiratory failure. Complete atrioventricular canal, prune belly syndrome and omphalocele have been reported in lethally affected males. Intelligence is normal. In females, the syndrome presents with bone dysplasia and facial dysmorphism. Males born to affected mothers show a lethal course of the disease in the embryonic or perinatal period.
Etiology
MNS is caused by gain of function mutations in the gene FLNA (Xq28) that encodes the actin-binding cytoskeletal protein filamin A. Several lines of evidence suggest that filamin participates in the remodeling of the cytoskeleton during development by integrating cell signaling events with subsequent alterations in cellular shape and motility. MNS is allelic with 4 other skeletal dysplasias (otopalatodigital syndrome type 1 and 2 (OPD1 and OPD2, respectively), terminal osseous dysplasia - pigmentary defects (TOD) and frontometaphyseal dysplasia (FMD).
Genetic counseling
MNS is inherited in an X-linked dominant manner. Male-to-male transmission has not been reported. The risk of transmitting the mutation in each pregnancy is 50%; males inheriting the mutation will be affected while females who inherit the mutation are less severely affected.

                            Last update: 
                            May 2015


                            - Expert reviewer(s): 
                            Pr Stephen ROBERTSON