Diseases

Maternally Inherited Leigh Syndrome

Maternally Inherited Leigh Syndrome: A rare condition where Leigh syndrome is inherited from the mother. Leigh syndrome is characterized by degeneration of the brain and impaired function of various organs.

Mathieu De Broca Bony syndrome

Mathieu de broca bony syndrome (medical condition): A very rare syndrome characterized by a cleft palate, short stature and abnormalities of the vertebrae in the spine.

Matsoukas Liarikos Giannika syndrome

Matsoukas-Liarikos-Giannika syndrome: A very rare syndrome characterized mainly by mental retardation, short stature and eye and joint abnormalities.

Maturity onset diabetes of the young

Maturity-onset diabetes of the young (MODY) is an uncommon form of diabetes that is caused by a genetic defect inherited from either parent. It is sometimes considered a subgroup of type 2 diabetes but differs in several ways from the standard form of that disease. It can also be misdiagnosed as type 1 diabetes or other forms of diabetes. MODY is most often diagnosed in teens or young adults of normal weight and build. It is sometimes seen in children as young as 6 years old. Several genetic defects have been identified in MODY patients. Of the eight known types of MODY, most can be controlled by diet alone or through antidiabetic agents. However, certain types of MODY require insulin therapy. The offspring of a person with MODY have a 50 percent risk of developing the condition. Because of this, MODY is often present in at least two generations of a patient’s family.

Maumenee syndrome

Maumenee syndrome: A rare inherited disorder characterized by deafness at birth and corneal dystrophy which impairs vision.

Maxillary double lip

Maxillary double lip: A rare defect where the upper lip is duplicated and is noticeable when smiling.

Maxillofacial dysostosis

Maxillofacial dysostosis: A rare inherited disorder characterized by jaw, ear and eye abnormalities as well as speech problems.

May-Hegglin anomaly

May-Hegglin Anomaly: An inherited blood disorder involving abnormalities in some of the blood components (platelets and certain leukocytes).

McAlister Crane syndrome

Mcalister crane syndrome (medical condition): A very rare syndrome characterized mainly by short arms and legs and resulting in stillbirth or infant death

McCallum Macadam Johnston syndrome

Mccallum macadam johnston syndrome (medical condition): A rare inherited genetic syndrome characterized by mental retardation, coarse facial features and capillary hemangiomas.

McCune Albright syndrome

McCune-Albright syndrome is a disorder that affects the bones, skin, and several hormone-producing (endocrine) tissues.
People with McCune-Albright syndrome develop areas of abnormal scar-like (fibrous) tissue in their bones, a condition called polyostotic fibrous dysplasia. Polyostotic means the abnormal areas (lesions) may occur in many bones; often they are confined to one side of the body. Replacement of bone with fibrous tissue may lead to fractures, uneven growth, and deformity. When lesions occur in the bones of the skull and jaw it can result in uneven (asymmetric) growth of the face. Asymmetry may also occur in the long bones; uneven growth of leg bones may cause limping. Abnormal curvature of the spine (scoliosis) may also occur. Bone lesions may become cancerous, but this happens in fewer than 1 percent of people with McCune-Albright syndrome.

In addition to bone abnormalities, affected individuals usually have light brown patches of skin called café-au-lait spots, which may be present from birth. The irregular borders of the café-au-lait spots in McCune-Albright syndrome are often compared to a map of the coast of Maine. By contrast, café-au-lait spots in other disorders have smooth borders, which are compared to the coast of California. Like the bone lesions, the café-au-lait spots in McCune-Albright syndrome often appear on only one side of the body.

Girls with McCune-Albright syndrome usually reach puberty early. These girls usually have menstrual bleeding by age two, many years before secondary sex characteristics such as breast enlargement and pubic hair are evident. This early onset of menstruation is believed to be caused by excess estrogen, a female sex hormone, produced by cysts that develop in one of the ovaries. Less commonly, boys with McCune-Albright syndrome may also experience early puberty.

Other endocrine problems may also occur in people with McCune-Albright syndrome. The thyroid gland, a butterfly-shaped organ at the base of the neck, may become enlarged (a condition called a goiter) or develop masses called nodules. About 50 percent of affected individuals produce excessive amounts of thyroid hormone (hyperthyroidism), resulting in a fast heart rate, high blood pressure, weight loss, tremors, sweating, and other symptoms. The pituitary gland (a structure at the base of the brain that makes several hormones) may produce too much growth hormone. Excess growth hormone can result in acromegaly, a condition characterized by large hands and feet, arthritis, and distinctive facial features that are often described as "coarse." Rarely, affected individuals develop Cushing's syndrome, an excess of the hormone cortisol produced by the adrenal glands, which are small glands located on top of each kidney. Cushing's syndrome causes weight gain in the face and upper body, slowed growth in children, fragile skin, fatigue, and other health problems.

McDonough syndrome

McDonough syndrome: A very rare syndrome characterized mainly by mental retardation and multiple birth abnormalities such as heart defects, undescended testes, curved spine and distinctive facial appearance.

McDowall syndrome

McDowall syndrome: A very rare syndrome characterized mainly by mental retardation and excessive skin folds and furrows on the scalp.

McGillivray syndrome

McGillivray syndrome: A very rare syndrome characterized mainly by heart defects, skull and facial abnormalities and ambiguous genitalia.

McKusick Kaufman syndrome

McKusick-Kaufman syndrome (MKS) is characterized by the triad of postaxial polydactyly (PAP), congenital heart disease (CHD), and hydrometrocolpos (HMC) in females and genital malformations in males (most commonly hypospadias, cryptorchidism, and chordee). HMC in infants usually presents as a large cystic abdominal mass arising out of the pelvis and is caused by dilatation of the vagina and uterus as a result of the accumulation of cervical secretions from maternal estrogen stimulation. HMC can be caused by failure of the distal third of the vagina to develop (vaginal agenesis), a transverse vaginal membrane, or an imperforate hymen. Cardiac malformations that have been described at least once in individuals with MKS include atrioventricular (AV) communis with a left-sided superior vena cava, atrial septal defect, ventricular septal defect, AV canal, small aorta and hypoplastic left ventricle, tetralogy of Fallot, and patent ductus arteriosus.

McPherson Clemens syndrome

Mcpherson clemens syndrome (medical condition): A very rare syndrome characterized by heart defects, malrotated intestines and various facial anomalies.

Meadows syndrome

Meadows syndrome: A rare condition that affects pregnant women during the last trimester or within two months after birth. It is characterized by breathing difficult, chest pain, congestive heart failure, heart rhythm abnormalities, high blood pressure, gastrointestinal symptoms and embolisms.

Meconium aspiration syndrome

Meconium aspiration syndrome (MAS, alternatively "Neonatal aspiration of meconium") is a medical condition affecting newborn infants. It occurs when meconium is present in their lungs during or before delivery. Meconium is the first stool of an infant, composed of materials ingested during the time the infant spends in the uterus.

Meconium is normally stored in the infant's intestines until after birth, but sometimes (often in response to fetal distress) it is expelled into the amniotic fluid prior to birth, or during labor. If the baby then inhales the contaminated fluid, respiratory problems may occur.

MECP2 duplication syndrome

MECP2 duplication syndrome is a condition that occurs almost exclusively in males and is characterized by moderate to severe intellectual disability. Most people with this condition also have weak muscle tone in infancy, feeding difficulties, poor or absent speech, seizures that may not improve with treatment, or muscle stiffness (spasticity). Individuals with MECP2 duplication syndrome have delayed development of motor skills such as sitting and walking. Some affected individuals experience the loss of previously acquired skills (developmental regression). Approximately one third of people with this condition cannot walk without assistance. Many individuals with MECP2 duplication syndrome have recurrent respiratory tract infections. These respiratory infections are a major cause of death in affected individuals, with almost half succumbing by age 25.

MED 23 gene defect

Not much information is available on this ultra-rare gene defect. The known incidence is limited to two separate families (one in US, the other in Algeria). 

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)

MCAD deficiency is a metabolic disorder. MCAD is an enzyme found in the mitochondria that is responsible for the metabolism of medium chain fatty acids. When this enzyme is missing, the body is unable to convert these fatty acids to energy during times of decreased food intake. Individuals who are MCAD deficient are not able to fast for extended periods of time because of the inability to convert the body's fat to energy when the food store has run out. When individuals with MCAD do fast, they experience a range of serious life threatening symptoms or even death.

Medrano Roldan syndrome

Medrano-Roldan syndrome: A very rare syndrome characterized mainly by mental retardation, reduced muscle tone and increased skin pigmentation.

Medullary cystic kidney disease 1

Medullary cystic kidney disease 1: A rare disorder characterized mainly by the development of kidney cysts and affects kidney function during adulthood. The disorder is caused by a genetic defect (chromosome 1q21). More detailed information about the symptoms, causes, and treatments of Medullary cystic kidney disease 1 is av