Marfan syndrome
Marfan syndrome (also called Marfan's syndrome) is a genetic disorder of the connective tissue.
It is sometimes inherited as a dominant trait. It is carried by a gene called FBN1, which encodes a connective protein called fibrillin-1.[1][2] People have a pair of FBN1 genes. Because it is dominant, people who have inherited one affected FBN1 gene from either parent will have Marfan's. This syndrome can run from mild to severe.
People with Marfan's are typically tall, with long limbs and long thin fingers.
The most serious complications are the defects of the heart valves and aorta. It may also affect the lungs, eyes, the dural sac surrounding the spinal cord, skeleton and the hard palate.
In addition to being a connective protein that forms the structural support for tissues outside the cell, the normal fibrillin-1 protein binds to another protein, transforming growth factor beta (TGF-β).[3] TGF-β has deleterious effects on vascular smooth muscle development and the integrity of the extracellular matrix. Researchers now believe that secondary to mutated fibrillin there is excessive TGF-β at the lungs, heart valves, and aorta, and this weakens the tissues and causes the features of Marfan syndrome. [4]Since angiotensin II receptor blockers (ARBs) also reduce TGF-β, they have tested this by giving ARBs (losartan, etc.) to a small sample of young, severely affected Marfan syndrome patients. In some patients, the growth of the aorta was indeed reduced.[5]
It is named after Antoine Marfan,[6] the French pediatrician who first described the condition in 1896 after noticing striking features in a 5-year-old girl.[7][8] The gene linked to the disease was first identified by Francesco Ramirez at the Mount Sinai Medical Center in New York City in 1991.[9]
Marfan syndrome Symptoms
Although there are no unique signs or symptoms of Marfan syndrome, the constellation of long limbs, dislocated lenses, and aortic root dilation is sufficient to make the diagnosis with confidence. There are more than 30 other clinical features that are variably associated with the syndrome, most involving the skeleton, skin, and joints. There is a great deal of clinical variability even within families that carry the identical mutation.
Skeletal system
The most readily visible signs are associated with the skeletal system. Many individuals with Marfan syndrome grow to above average height. Some have long slender limbs with long fingers and toes (arachnodactyly). This condition of elongated limbs is known as dolichostenomelia. An individual's arms may be disproportionately long, with thin, weak wrists. In addition to affecting height and limb proportions, Marfan syndrome can produce other skeletal anomalies. Abnormal curvature of the spine (scoliosis) is common, as is abnormal indentation (pectus excavatum) or protrusion (pectus carinatum) of the sternum. Other signs include abnormal joint flexibility, a high palate, malocclusions, flat feet, hammer toes, stooped shoulders, unexplained stretch marks on the skin and thin wrists. It can also cause pain in the joints, bones and muscles in some patients. Some people with Marfan have speech disorders resulting from symptomatic high palates and small jaws. Early osteoarthritis may occur.
Eyes
Marfan syndrome can also seriously affect the eyes and vision. Nearsightedness and astigmatism are common, but farsightedness can also result. Subluxation (dislocation) of the crystalline lens in one or both eyes (ectopia lentis) (in 80% of patients) also occurs and may be detected by an ophthalmologist or optometrist using a slit-lamp biomicroscope. In Marfan's the dislocation is typically superotemporal whereas in the similar condition homocystinuria, the dislocation is inferonasal. Sometimes eye problems appear only after the weakening of connective tissue has caused detachment of the retina.[10] Early onset glaucoma can be another related problem.
Cardiovascular system
The most serious signs and symptoms associated with Marfan syndrome involve the cardiovascular system. Undue fatigue, shortness of breath, heart palpitations, racing heartbeats, or Angina pectoris with pain radiating to the back, shoulder, or arm. Cold arms, hands and feet can also be linked to Marfan's syndrome because of inadequate circulation. A heart murmur, abnormal reading on an EKG, or symptoms of angina can indicate further investigation. The signs of regurgitation from prolapse of the mitral or aortic valves (which control the flow of blood through the heart) result from cystic medial degeneration of the valves which is commonly associated with Marfan's syndrome (see mitral valve prolapse, aortic regurgitation). However, the major sign that would lead a doctor to consider an underlying condition is a dilated aorta or an aortic aneurysm. Sometimes, no heart problems are apparent until the weakening of the connective tissue (cystic medial degeneration) in the ascending aorta causes an aortic aneurysm or aortic dissection, a medical emergency. An aortic dissection is most often fatal and presents with pain radiating down the back, giving a tearing sensation.
Because of the underlying connective tissue abnormalities that cause Marfan syndrome, there is an increased incidence of dehiscence of prosthetic mitral valve.[11] Care should be taken to attempt repair of damaged heart valves rather than replacement.
During pregnancy, even in the absence of preconceived cardiovascular abnormality, women with Marfan syndrome are at significant risk of aortic dissection, which is often fatal even when rapidly treated. For this reason, women with Marfan syndrome should receive a thorough assessment prior to conception, and echocardiography should be performed every six to ten weeks during pregnancy, to assess the aortic root diameter. For most women, safe vaginal delivery is possible.[12]
Lungs
Marfan syndrome is a risk factor for spontaneous pneumothorax. In spontaneous unilateral pneumothorax, air escapes from a lung and occupies the pleural space between the chest wall and a lung. The lung becomes partially compressed or collapsed. This can cause pain, shortness of breath, cyanosis, and, if not treated, death. Marfan syndrome has also been associated with sleep apnea and idiopathic obstructive lung disease.
Central nervous system
Another condition that can reduce the quality of life for an individual, though not life-threatening, is dural ectasia, the weakening of the connective tissue of the dural sac, the membrane that encases the spinal cord. Dural ectasia can be present for a long time without producing any noticeable symptoms. Symptoms that can occur are lower back pain, leg pain, abdominal pain, other neurological symptoms in the lower extremities, or headaches. Such symptoms usually diminish when the individual lies flat on his or her back. These types of symptoms might lead a doctor to order an X-ray of the lower spine. Dural ectasia is usually not visible on an X-ray in the early phases. A worsening of symptoms and the lack of finding any other cause should eventually lead a doctor to order an upright MRI of the lower spine. Dural ectasia that has progressed to the point of causing these symptoms would appear in an upright MRI image as a dilated pouch that is wearing away at the lumbar vertebrae.[10] Other spinal issues associated with Marfan include degenerative disk disease and spinal cysts. Marfan syndrome is also associated with dysautonomia.
Central nervous system
- Another condition that can reduce the quality of life for an individual, though not life-threatening, is dural ectasia, the weakening of the connective tissue of the dural sac, the membrane that encases the spinal cord. Dural ectasia can be present for a long time without producing any noticeable symptoms. Symptoms that can occur are lower back pain, leg pain, abdominal pain, other neurological symptoms in the lower extremities, or headaches. Such symptoms usually diminish when the individual lies flat on his or her back. These types of symptoms might lead a doctor to order an X-ray of the lower spine. Dural ectasia is usually not visible on an X-ray in the early phases. A worsening of symptoms and the lack of finding any other cause should eventually lead a doctor to order an upright MRI of the lower spine. Dural ectasia that has progressed to the point of causing these symptoms would appear in an upright MRI image as a dilated pouch that is wearing away at the lumbar vertebrae.[10] Other spinal issues associated with Marfan include degenerative disk disease and spinal cysts. Marfan syndrome is also associated with dysautonomia.
- Aortic aneurysm or dilation
- Arachnodactyly
- GERD
- Bicuspid aortic valve
- Cysts
- Cystic medial necrosis
- Deviated septum[19]
- Dural ectasia
- Early cataracts
- Early glaucoma[20]
- Early osteoarthritis[21]
- Ectopia lentis
- Emphysema[22]
- Eye iris coloboma[23]
- Flat feet
- Gigantism
- Heart palpitations[24]
- Hernias
- Hypermobility of the joints
- Kyphosis (hunched back)
- Leaky heart valve
- Learning disability[23]
- Malocclusion
- Micrognathia (small lower jaw)[23]
- Mitral valve prolapse
- Myopia (near sightedness)
- Obstructive lung disease
- Osteopenia (low bone density)[25]
- Pectus carinatum or excavatum
- Pneumothorax (collapsed lung)
- Retinal detachment
- Scoliosis
- Sleep apnea
- Stretch marks not from pregnancy[26] or obesity
- Teeth crowded[26]
- "Narrow, thin face"[23]
- Temporomandibular joint disorder (TMD)[27]
Differential Marfan syndrome diagnosis
The following disorders have similar signs and symptoms of Marfan syndrome:
- Congenital Contractural Arachnodactyly (CCA) or Beals Syndrome
- Ehlers-Danlos syndrome
- Homocystinuria
- Loeys-Dietz syndrome
- MASS phenotype
- Shprintzen-Goldberg syndrome [28]
- Stickler syndrome
- Multiple endocrine neoplasia, type 2B