Marfan syndrome

Introduction to Ma Fang Syndrome Ma Fang syndrome also has congenital mesoderm dysplasia, called Marchesani syndrome, spider indications, limb slenderness, characterized by surrounding connective tissue malnutrition, skeletal abnormalities, internal eye diseases and cardiovascular abnormalities. A hereditary disease characterized by connective tissue. Through the family's linkage gene mapping dominant inheritance, it can be proved from the increase of urinary hydroxyproline excretion in patients, the disease is elastic fiber defect, and there is abnormal collagen metabolism. basic knowledge The proportion of sickness: 0.004% - 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: aortic stenosis thoracic aortic dissection aneurysm crystal dislocation myopia glaucoma iritis subarachnoid hemorrhage epilepsy spina bifida syringomyelia

Cause of Ma Fang Syndrome

Genetic factors (85%)

The disease is autosomal dominant, and Dietz et al. (1991) localize the disease gene to 15q15~q21.3 through family linkage analysis, in many tissues such as endocardium, heart valve, large blood vessels, bones, etc. There are accumulations of mucopolysaccharides such as chondroitin sulfate A or C, which affect the structure and function of elastic fibers and other connective tissue fibers, causing corresponding organ dysplasia and dysfunction. Abraham et al. (1982) proposed aortic elasticity. The protein is abnormal, the desmosome protein and the isopontin protein are decreased, and the lysyl residue is correspondingly increased, which is the main change of the disease. The urinary hydroxyproline excretion is increased, and the blood mucin and mucopolysaccharide are also Increase.

Pathogenesis

Through the family's linkage gene localization dominant inheritance, it can be proved from the increase of urinary hydroxyproline excretion in patients, this disease is elastic fiber defect, that is, abnormal collagen metabolism, connective tissue fiber is a very important component in the body tissue structure Therefore, when it is abnormal, it will affect the organs of the whole body (mesoderm tissue), especially the bones and cardiovascular system. The spider bones and the chest or the chest of the boat are all represented by the limbs. The excessive growth of the longitudinal axis of the fingers and ribs may be due to defects in the composition of the periosteal fibers. There is an acidic mucopolysaccharide deposit in the middle layer of the aorta and pulmonary artery. The disease has a family tendency and is autosomal dominant.

Pathology: gross eye changes, ascending aorta dilatation, chronic aortic dissection, heart valve showed mucinous edema, valve balloon, chord thickening, cardiac hypertrophy and mitral calcification and dermatoglyph Abnormalities, etc., the pathological changes of this syndrome are most prominent and representative of the cardiovascular system. Microscopically, the aortic middle layer elastic tissue is sparse and fragmented, with smooth muscle changes in irregular thread shape, and the amount of collagen increases. It can be seen that the metachromatic substance is scattered in the middle layer, and the aortic dissection is formed. It shows cystic middle necrosis and moderate degeneration of elastic fibers, accompanied by smooth muscle bundle disorder. The histopathological changes of the aortic valve are Normal structural destruction and loss, cystic degeneration and loss of tissue fibroblasts, pathological changes in the skin manifested as vacuolar degeneration and elastic fiber arrangement disorder, joint synovial changes are also elastic fibrosis, collagen increase and metachromatic substances It is scattered in the sac.

Ma Fang syndrome prevention

There are four measures to prevent horse syndrome:

1. Ma Fang syndrome drug treatment, the main purpose is to slow or delay the occurrence of cardiovascular disease, prevention and treatment of ventricular arrhythmia.

2. Regular follow-up review, life-long application of beta blockers.

3. Limiting the amount of physical activity can slow down and delay the onset and development of cardiovascular disease.

4. Early diagnosis, early treatment, as far as possible to find the pathogen, to treat the cause.

Complications of horse syndrome Complications aortic stenosis thoracic aortic dissection aneurysm crystal dislocation myopia glaucoma iritis subarachnoid hemorrhage epilepsy spina bifida syringe

1. Cardiovascular is most likely complicated by aortic idiopathic dilatation, aortic stenosis, aortic dissection and mitral anomalies.

2. Eye lesions can be complicated by crystal dislocation or subluxation, high myopia, glaucoma, retinal detachment, iritis and so on.

3. Nervous system lesions can be complicated by subarachnoid hemorrhage and internal carotid aneurysm, epileptic seizures, in addition, patients with Ma Fang syndrome can also have spina bifida, spinal cord bulging, syringomyelia.

Symptoms of horse syndrome Syndrome Common symptoms Thumb sign tremor arrhythmia angina pectoris lens dislocation or subluxation wrist sign cyst dural bulging joint relaxation mitral valve prolapse

Skeletal lesion

It is the main lesion, and it is easy to prompt the diagnosis, the incidence rate is 80% to 97.2%.

(1) The body is thin and tall, and the limbs are slender, especially the forearms and thighs:

1 height is more > 180cm.

2 finger distance> height (two hands flat extension, two middle finger distance - height > 7.6cm, has diagnostic value.

3 lower body (from pubic symphysis to sole) > upper body (from the top of the head to the pubic symphysis), the ratio of > 0.92 (normal person 0.92).

(2) Spider finger/toe-like changes:

1 finger (toe) is particularly long, with a typical spider-like change, the ratio of hand to height is >11%, and the ratio of foot to height is >15%.

2 thumb sign (thumb sign): thumb adduction, the remaining 4 fingers clenched fist, the tip of the thumb beyond the lower edge of the palm, accounting for about half of the patient with this disease.

3 wrist sign (wrist sign): Hold the hand under the styloid process of the other hand with one hand, the thumb and the little finger can be contacted under no pressure, with 82% of the sign.

4 metacarpal index and phalanx index increased, normal metacarpal index <8, the patient's metacarpal index> 8.4 (8.4 ~ 10.5), 5 other finger (toe) abnormalities: there may be clubbing, refers to ( Toe) , palms thin, flat feet.

(3) Skull lesions:

1 long, narrow, convex;

2 head index > 75.9.

3 The distance between the eyes is too wide or too narrow, and the jaw is long.

4 teeth are not aligned, lack of wisdom teeth and so on.

5 ears stretched forward or drooping, the ear wheel is thin, shaped like an old man.

(4) Chest, spinal deformity changes:

1 chicken breast, flat chest, funnel chest;

2 hunchback, spine or spine.

2. Eye lesions

The incidence rate is 63.8% to 68.3%.

(1) Dislocation or subluxation of bilateral lens, the incidence of which accounted for 83% to 86.8% of ocular lesions, and all patients with high dislocation.

(2) Retinal detachment, iris tremor, cataract (occurring in the late stage of the disease), strabismus, pupil dilation, secondary glaucoma, etc.

3. Cardiovascular disease

It is one of the main clinical features of this disease, which can be as early as 5 years old, as late as 60 years old, and is progressive, with a clinical incidence rate of 38.5% to 60%; the incidence of pathological examination is 95% to 100%, the main lesion is Necrosis of the aorta, cystic dilatation.

(1) aortic lesions: according to the incidence of aortic root dilatation with aortic valve insufficiency, ascending aortic aneurysm, aortic dissection, etc., Bowers believes that with or without aortic regurgitation Aortic dilation is one of the characteristics of diagnosis of Ma Fang syndrome; and there are aortic regurgitation, mostly male, whose diastolic murmur is different from that of rheumatic aortic regurgitation, mostly located on the right sternal border. Between 2 and 4 intercostals, some scholars have pointed out in recent years that the separation of the dissection of pregnant women is mostly Ma Fang syndrome.

(2) mitral valve prolapse: due to mitral valve mucoid degeneration, the valve leaflets become thin, too long or chordae tendon elongation caused by mitral valve prolapse, severe cases of mitral insufficiency.

(3) Coronary artery involvement: causing angina or myocardial infarction.

(4) Other congenital cardiovascular malformations: such as atrial septal defect, ventricular septal defect, patent ductus arteriosus, pulmonary umbilical stenosis and dilatation.

(5) Heart enlargement, arrhythmia, etc.

Cardiovascular disease is the main cause of death in Ma Fang syndrome, accounting for 70% to 90% of the cause of death.

4. Central nervous system lesions

(1) Dural bulging: It is one of the characteristics of this disease. It is more common in the lumbosacral dural bulging. Its characteristics are:

1 The incidence rate is high (63% to 66.7%).

2 has no relationship with the severity of other three signs (skeletal deformity, lens dislocation, aortic disease).

3 more asymptomatic.

4 need to rely on X-ray photos, CT / MRI and other inspections can be found.

5 can also be combined with meningioma, caused by defects in extracellular matrix.

(2) Subarachnoid cysts.

(3) pelvic meningocele.

5. Other parts

(1) Subcutaneous fat is rare and muscle development is poor.

(2) joint relaxation, expansive shrinkage lines or wrinkles.

(3) Inguinal hernia, umbilical hernia, and transverse hernia.

Examination of Ma Fang syndrome

The basal metabolic rate is low, the serum mucin is lower than normal, the urinary hydroxyproline is increased, the mucopolysaccharide is increased, especially the sulfate gum A or C is increased, and the hyaluronic acid in the urine is excessive.

Regarding the determination of 24h urinary hydroxy citrate, some scholars have suggested that as a diagnostic indicator, the results of domestic Tongji Medical University data for 24h urinary hydroxy acid normal adults and children are (24.41±17.02) mg, patients (including adults, children) The difference between (44.84±36.12) mg is very significant. Although the test is less specific and less sensitive, it is obvious if the disease and other factors that can affect the urinary hydroxyproline test value are excluded. Increased is meaningful for diagnosis.

X-ray inspection

(1) The phalanx is slender.

(2) Determination of metacarpal index, that is, the ratio of the right and left 2nd to 5th metacarpal length and width, normal is 5.5 to 8.0; 8.1 to 8.3 prompt (possible) diagnosis, 8.4 confirmed the disease.

(3) Determination of the phalanx index, that is, the ratio of the length and width of the proximal phalanx of the right hand ring, female > 4.6, male > 5.6, can diagnose the disease.

(4) The aortic root width was significantly dilated, and the aortic retrograde angiography showed that the ascending aorta expanded in a vase-like manner and the left ventricle increased.

2. Echocardiography reported a diagnostic coincidence rate of 92.3%.

(1) Aortic root expansion: according to Brown et al.

1 aortic width > 22mm / m2 body surface area;

2 measured aortic diameter > 37mm;

3 left aortic diameter <0.7cm; 2 of 3 items can diagnose the disease.

(2) Aortic valve dysfunction.

(3) signs of mitral valve prolapse and mitral insufficiency signs.

(4) Those with aortic dissection can find the corresponding signs.

(5) Other cardiovascular malformations.

3. CT and or MRI examination can clearly identify the presence or absence of aortic lesions, vessel wall thickness, aortic dissection and tear, occlusion in the lumen.

4. Slit lamp examination can reveal lens dislocation.

Diagnosis and differentiation of Ma Fang syndrome

diagnosis

1. The diagnosis of this syndrome is based on

(1) Special bone changes, that is, the tubular bone is slender, especially the metacarpal bone, the cortical bone is thin, slender, and changes like a spider.

(2) Congenital cardiovascular abnormalities.

(3) Eye symptoms.

(4) Family history.

Three of the above four clinical criteria can be diagnosed, and only two of the first three changes can be diagnosed as incomplete equine syndrome.

2. Mckusick (1995) lists cardiovascular abnormalities in horse syndrome as

(1) aortic dilatation (ascending aorta, descending aorta), aortic dissection, aortic stenosis, patent ductus arteriosus.

(2) Pulmonary artery abnormalities (pulmonary artery dilatation, pulmonary aneurysm).

(3) septal defect (atrial septal defect, ventricular septal defect).

(4) abnormal valve and accompanied by subacute bacterial endocarditis.

Differential diagnosis

The disease must be differentiated from the following diseases:

1 homocysteine;

2 rheumatic aortic valve insufficiency;

3 familial mitral valve prolapse or aortic valve prolapse;

4 familial aortic annulus dilatation;

5 congenital contracture spider-like finger (toe) and other identification.

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