Achondroplasia in children

Introduction to pediatric cartilage hypoplasia Achilles achondroplasty (or cartilage dystrophy) is the most common type of pygmy, and it is a developmental abnormality of cartilage-deficient bone and normal membranous bone. It is accompanied by a short limb, a large head and a trigeminal deformity with frequent hands. It is an autosomal dominant hereditary disease. Most affected individuals show new gene mutations. Only a few cases are familial cartilage dystrophy. The older the mother, the higher the incidence of babies. basic knowledge The proportion of the disease: 0.05% (the incidence rate of children under 6 years old is about 0.05%) Susceptible people: children Mode of infection: non-infectious Complications: malnutrition

Pediatric dysplasia etiology

(1) Causes of the disease

Pediatric dysplasia (or cartilage dystrophy) is an autosomal dominant hereditary disease. Most affected individuals appear as new gene mutations. Only a few cases are familial cartilage dystrophy. The older the mother, the higher the incidence of the child born. 50% of male patients are inherited according to Mendelian law, and can even be passed down from generation to generation. Women are almost inherited. There were no endocrine disorders in the sick children.

(two) pathogenesis

The bone defect of cartilage is due to defects in the original gene protoplasm. About 80% of cases are distributed to families with normal parents and brothers. May be caused by a dominant gene mutation. This disease is often accompanied by calf varus deformity, and atlantoaxial instability and spinal stenosis. The reason for this is that the gene encoding fibroblast growth factor receptor-3 (FGFR3) undergoes point mutation. This mutation almost always occurs (98%) in the same nucleotide (No. 1138) and causes a single amino acid change (arginine to glycine) in the transmembrane region of the cell surface receptor. This receptor is expressed in all pre-bone cartilage and is diffusely expressed in the central nervous system.

The pathological changes are mainly in the growth of the cartilage of the tarsal plate. The chondrocytes are sparse, irregularly arranged, and mucous degeneration occurs. The cancellous bone trabeculae are irregular, although the calcification is normal, but the length of the long bone grows very slowly. Because the periosteal bone is not affected, the diameter of the long bone backbone develops normally. Occasionally, the blood vessels from the periosteum to the epiphyseal plate have connective tissue hyperplasia, and a fibrous band appears across the transverse diameter of the bone, thereby closing the sacral line and hindering the development of the diaphysis.

Pediatric dysplasia prevention

Do a good job in genetic disease counseling, avoid maternal pregnancy, do a good job in pregnancy, and prevent various infectious diseases.

Avoid genetic diseases.

Methods to prevent genetic diseases:

Avoiding close relatives marriage: The intelligence of children with children born in close relatives is much worse than that of non-close relatives, and the incidence rate is very high. So be sure to avoid close relatives getting married.

Avoid old age: the childbearing age is best not to exceed 35 years old, because the aged women's cells are aging, susceptible to external virus infection, individuals formed after fertilization are prone to chromosomal diseases.

Conducting fertility counseling: Have you ever had a child with mental retardation or disability, or if the child died of illness, and whether the child will have the same situation; the woman is a habitual abortion, can he give birth again, how to prevent it; women have suffered during pregnancy Whether it affects the fetus, whether it has been treated with certain drugs, has been exposed to chemical poisons, or has worked in a radioactively contaminated position. Through consultation, the doctor will perform necessary examinations on both sides of the couple, and will give a treatment method and accurate advice.

Administrative department consultation: The health administrative department or the family planning department consults with medical genetic workers when formulating relevant eugenic policies. For example, whether the formulation of certain eugenics regulations and regulations is reasonable; what are the countermeasures for the control of common genetic diseases in a certain region? How to investigate the investigation of certain genetic diseases. Therefore, newlyweds should go to the relevant administrative department for consultation.

Termination of pregnancy: If you are pregnant and have been found to have a serious illness, stop the pregnancy as soon as possible.

Pediatric dysplasia complications Complications malnutrition

Often accompanied by malnutrition, poor growth, diarrhea often accompanied by dehydration, acidosis, and even cause shock (campria syndrome), but also arthritis, chronic unexplained hepatitis and severe enamel dysplasia. In adulthood, due to the narrowing of the spinal canal, it may be accompanied by neurological complications. Multiple disc herniation can compress the spinal cord and spinal nerves, causing back pain, sciatica, and even paralysis. Often due to the abnormality of the body, there is a feeling of inferiority, so excited.

Symptoms of pediatric cartilage hypoplasia Common symptoms Face size and limb deformity Forehead and humerus protrusion Head enlargement Mandibular anterior knee Knee valgus or hip varus thoracic deformity Epiphysis closure

Signs at birth are already evident, with the most prominent gnomes, mainly short limbs, especially the upper arm and thigh, and the trunk is still normal. The appearance of the sick child gives the impression that "the adult's torso, the child's limbs." When standing upright, the tip of the finger does not touch the big trochanter, and the tip of the normal finger reaches the upper part of the thigh. The midpoint of normal body height is in the umbilicus, while the midpoint of the sick child is at the lower end of the sternum. The head is enlarged, the face is wide, the forehead is prominent, the bridge of the nose is flat, the upper cove is protruding, and the mandible is protruding. The teeth are normal. Although the length of the thorax is normal, it is flat, the cost of the rib is everted, the posterior process of the thoracolumbar section of the spine is enlarged, and the abdomen is protruding and the buttocks are posterior to form a special posture. The hand is short and wide, and the middle finger is shorter than normal. Therefore, it is equal to other fingers. The middle finger is separated from the fourth finger by a "V" type.

The proximal end of the humerus often has a varus deformity, causing the lower extremities to bend. Irregularity of the bone end can affect joint activities, such as stretching of the elbow and forearm rotation, gait swing. Muscle development is beyond normal, the skin is soft and slack, and the formation of skin and subcutaneous tissue is formed. Generally, endocrine and sexual function are normal, and intelligence is normal.

Examination of pediatric cartilage hypoplasia

Blood, urine, and stool routine examinations were normal.

X-ray inspection:

1. Head: The top of the skull is enlarged, while the skull base and the occipital bone are narrow.

2. Tubular bone: All tubular bones become shorter, the diameter is relatively thicker, and the density is increased, especially in the proximal end of the extremities such as the femur and tibia. The cortical bone at the muscle attachment is thickened, and the metaphyseal end is significantly thicker. The center of the seesaw is concave in the shape of a "U", which is most common in the knee joint. The palms, toes and phalanx are short and dense.

3. Sternum: The anteroposterior diameter can be reduced due to the short ribs. The sternum is thick, wide and short.

4. Tibia: The humerus is narrowed, the position is lower, the ischial notch becomes smaller, the humeral wing is deformed, and the upper and lower diameters are short and kidney-shaped. The acetabulum is wide and flat, and the width of the pelvis is greater than the depth.

5. Spine: The length of the spine is normal, but the lumbosacral spine is excessively curved, and the distance between the pedicles of the first to fifth lumbar vertebrae is gradually reduced. Lateral vertebral arch shortening, resulting in spinal stenosis.

Diagnosis and diagnosis of pediatric cartilage hypoplasia

diagnosis

Diagnosis can be made based on relevant symptoms and X-ray examination.

Differential diagnosis

This disease should be identified with pygmy diseases that cause short stature, such as rickets, cretinism, pituitary dysfunction, achondroplasia, etc., but the short stature of this disease is mainly due to the lower jaw, humerus and elbow below the knee. Due to the short ulna and radius, it is not difficult to identify the clinical appearance or X-ray examination.

Hypochondroplasia: The pygmy performance is not very obvious.

Spondylo-epiphyseal dysplasia: also a short-limb pygmy often with a proximal large joint destruction. The normal vertebral body of the skull has a vertebral ossification center that fits into the thoracic dysplasia such as a bell shape.

Rickets and cretinism: rickets have typical clinical and X-ray findings that are easily differentiated; cretinism is often associated with mental retardation.

Vitamin D deficiency: manifested as blurred contours and ossification.

Pseudochondral hypoplasia: a rare cartilage development disorder. Named for body shape similar to cartilage hypoplasia. In essence, it is a vertebral dysplasia--- pseudo-hypercoronary hypoplasia.

Multiple osteophyte dysplasia (Catal's disease): a hereditary disorder of unknown cause, family-like, short-legged dwarf. Cartilage dysfunction is limited to cartilage, and one epiphysis can have multiple ossification centers during the same period.

Dysplasia of the metaphysis: a developmental abnormality caused by a cartilage-induced bone disorder in the long bone of the body. The main clinical manifestations are short-limb dwarfs, large joints and movement disorders.

Late-onset vertebrae dysplasia (STD): This disease is a rare torso-type dwarf caused by a rare spinal and limb joint developmental disorder. For concomitant recessive inheritance, female transmission, only male onset, similar to hemophilia. Pathologically, the developmental abnormalities of articular cartilage and bone are similar to those of Moque's syndrome, but only mildly. X-ray changes were mainly in the spine, pelvis and large joints, and there was no significant change in limb development, unlike Moique's syndrome.

Dense bone dysplasia: This disease is characterized by gnomes and general genetic disorders. The 22nd pair of chromosome G groups were missing one of the short arms.

Pituitary dwarf: may be due to congenital hypoplasia, dysplasia of the anterior pituitary caused by growth and development disorders. Most of the causes are unknown. A small number of pituitary lesions or systemic diseases affect the function of pituitary gland.

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