Characteristics of mucopolysaccharide disease type I.H
Mucopolysaccharide disease type I.H, also known as Hurler syndrome, is the most severe type of disease in this group. Most children die as a result of progressive exacerbations of their condition as a teenager. The underlying defect of the disease is the lack of α-L-aidu glycosidase, which causes dermatin and heparan sulfate to accumulate in tissues and be excreted in the urine. These children are mainly manifested by the accumulation of a large number of mucopolysaccharides and lipids in the brain tissue, and the separation of collagen fibers in bundles, resulting in joint deformities and stiffness; The meninges thicken, hydrocephalus, and the peripheral nerves are squeezed. Coronary artery stenosis, thickening of valves and endocardium, and myocardial stiffness can lead to congestive heart failure as the disease progresses.
In addition to being short stature, the clinical manifestations of children with Hurler syndrome are normal at birth, and parents can detect mild intellectual backwardness at the age of 1. Physical examination reveals hepatosplenomegaly and posterior thoracic protrusion. After the age of 1 year, the child's face begins to become rough, the chest cavity is small, the upper end is dysplastic, the hunchback is formed, the head is large like a boat, the neck is short, the boat-shaped head is prominent, the nose bridge is low and flat, the nostrils are wide, the mouth is large, the lips are thick, and the tongue is large. Around one year old, the cornea is cloudy, the physique and intellectual development are lagging behind, and after 1-2 years, the disease develops more rapidly, the joints are flexed, stiff, the fingers are claw-shaped, and there are often umbilical hernias and inguinal hernias. Most of them die in their teens.
X-rays of patients with Hurler syndrome may reveal multiple bone dysplasia, long head, thickened skull cap, and a boot-shaped or J-shaped sella. The vertebral body of the thoracic segment is ovoid, with an ornithischian protrusion on the anterior and lower margins, and the upper end is dysplasia, thus forming a humpback. The ribs are oared or streamer-shaped, the iliac wings are turned outwards, and the acetabular molars become shallow. Hip valgus, sometimes resembling aseptic necrosis. The distal phalangeal bone becomes thinner, the distal metacarpal becomes wider, and the proximal end narrows, with the fifth metacarpal as the focus. Long bones, especially those of the upper extremities, are irregularly widened, the cortex thins, the medullary is widened, and occasionally the cortex thickens. The radius is bent towards the ulna, and the joint surface of the ulnar radius is opposite, forming a V-shape.
02 Clinical diagnosis of mucopolysaccharide disease type I.H
Clinicians may confirm the diagnosis by measuring dermatin and heparin sulfate excreted in the urine, and α-L-aidu glycosidase activity of white blood cells, serum, or skin fibroblasts.
03 Characteristics and clinical diagnosis of mucopolysaccharide disease type I.S
Mucopolysaccharide type I.S is also known as Scheie syndrome. Patients are also due to α-L-aidu glucosidase deficiency. The disease is autosomal recessive. Prenatal diagnosis is the same as mucopolysaccharide type I.H.
Patients with this disease are obese, mildly rough face, inferior forehead protrusion, wide nose bridge, cornea turbidity, retinal degeneration, vision and hearing loss. Short neck, aortic valve lesions can produce heart murmurs, hepatosplenomegaly, inguinal hernia, normal intelligence. The toes of the fingers are wide and short, the fingers are straight and curved instead of claw-shaped, the joints are stiff, and the ribs are wide. Corticosteroid sulfate is also excreted in the urine.
Mucopolysaccharide disease type II
01 Characteristics and clinical diagnosis of mucopolysaccharide disease type II
Mucopolysaccharide type II, also known as Hunter syndrome, is inherited in an X-linked recessive fashion, and girls are less likely to suffer from the disease. Patients with this disease are caused by leukocyte and fibroblast deficiency of aidu glycolinate lipase sulfate.
The patient is short stature, rough face, large head, no cornea cloudiness, wide nose bridge, thick lip and wide gap between teeth, deafness, myocardial and heart valve mucopolysaccharide accumulation leading to heart enlargement, heart failure; Swelling of the abdomen, enlargement of the liver and spleen, inguinal hernia, umbilical hernia, thick hair, intellectual backwardness of varying degrees; Limited joint mobility, curvature, short and wide fingers, chicken breasts, knees varus. The clinical picture of the disease in boys is similar to that of type I, but the back is not hunched and there is no corneal opacity. After the age of 10, most of them became frightened and then their condition worsened, and in severe cases, they died as teenagers.
At present, prenatal diagnosis is carried out clinically during pregnancy, and amniotic fluid measurement enzymes or amniotic fluid metabolites are taken to determine whether the fetus has this disease.
Mucopolysaccharide disease type IV
01 Characteristics and clinical diagnosis of mucopolysaccharide disease type IV
Mucopolysaccharide type IV is also known as Morquio syndrome. There are two types of the disease, type A is caused by galactose 6 sulfolase deficiency, and type B is caused by galactosidase deficiency. The incidence is approximately 1 in 40,000 (live births).
Clinically, it is mainly manifested as short trunk and shortness. The patient has a normal face, with turbid cornea, short neck, chicken chest, flat thoracic vertebral body, and narrow discs, making the thoracic spine appear slubed. Thus the trunk is shortened and the limbs are longer. Patients have normal intelligence and dysplasia of the dentate process, which can cause atlantoaxial and pivotal dislocations, compression of the spine, and sudden death. In addition, patients often have lumbar protrusions, X-shaped legs, etc. Urinary tests may reveal the excretion of keratin sulfate and chondroitin sulfate.
At present, clinically, this disease can only be treated symptomatically. There is no prenatal diagnostic method.