cat calling syndrome
Introduction
Introduction to Pediatric Medication Syndrome Catscrysyndrome (catscrysyndrome) is a chromosome deletion syndrome caused by short arm loss (5p deletion) of chromosome 5, also known as short arm loss syndrome of chromosome 5, which is one of the most typical chromosomal deletion syndromes. The main clinical manifestations are the cat crying at birth, the typical deformity of the head and face, the small head round face, wide eye distance, small lower jaw, strabismus, wide flat nose and low ear, etc., poor growth and severe mental retardation. basic knowledge The proportion of illness: 0.0003%--0.0007% Susceptible people: children Mode of infection: non-infectious Complications: strabismus cataract
Cause
The cause of pediatric cat called syndrome
(1) Causes of the disease
The meow syndrome is caused by a short-armed deletion of chromosome 5 of group B, which is early replication, and most of the deletions are the result of two breaks. If the break occurs on the short arm and the long arm, respectively, a loop will be formed. Chromosomes, there are chromosome 5 translocations to C, D or G chromosomes, chimeras and arm inversions, etc. There are at least four reasons for the deletion of the chromosomes in theory: terminal deletion, intermediate deletion, The translocation and the short arm are not interchangeable. It is found that the missing part has 5p14, so 5p14 is considered to be the characteristic area of the meow syndrome. It is reported that the short length of the short arm is 30% of the short arm. The elders are 85%, generally 50%. There are also reports that 10% loss can also cause mild symptoms. From the perspective of chromosome changes, there is a gene with a pronunciation on the short arm of chromosome 5, when it is missing. , the variation of the pronunciation tone can occur.
(two) pathogenesis
Cytogenetic studies have confirmed that most short-armed deletions of chromosome 5 are caused by two breaks of chromosomes during mitosis. If the break occurs in the short arm, it is an intermediate deletion, if the break occurs in the short arm and the long arm, respectively. On the other hand, a circular chromosome is formed, and some children's chromosome 5 translocates to the C, D or G chromosome, forming a chimera or an inversion between arms.
The degree of clinical manifestation was related to the location of the 5p deletion, but there was no significant correlation with the length of the deletion. Therefore, it was suggested that the key areas should be determined according to the clinical manifestations of the child (cat crying and typical facial features). The key region of meow syndrome is located at 5p15.2, located between the DNA markers D5S713 and D5S18, which account for about 10% of the total length of 5p, containing 400-600kb DNA, providing a study for the disease. Genetic data.
Prevention
Pediatric meow syndrome prevention
Since 12% of meow syndrome is derived from a chromosomal balance translocation of one of the parents, it is important to have a chromosomal examination of the parent's parents to predict the likelihood of recurrence, reducing or eliminating the birth of the child.
The disease belongs to a class of hereditary diseases, and the preventive measures should be from pre-pregnancy to prenatal:
Pre-marital medical examination plays an active role in preventing birth defects. The size of the effect depends on the examination items and contents, including serological examination (such as hepatitis B virus, treponema pallidum, HIV), reproductive system examination (such as screening for cervical inflammation), Ordinary medical examinations (such as blood pressure, electrocardiogram) and asking about the family history of the disease, personal medical history, etc., do a good job in genetic disease counseling.
Complication
Pediatric meow syndrome complications Complications strabismus cataract
Growth disorders, strabismus, cataract, 1/3 cases may have congenital cardiovascular malformations, kidney and various skeletal deformities, spastic gait.
1. All kinds of causes such as aging, genetics, local dystrophies, immune and metabolic abnormalities, trauma, poisoning, radiation, etc., can cause lens metabolism disorders, resulting in lens protein degeneration and turbidity, called cataract, when the light is The opacity lens can't be projected on the retina, so you can't see the object. From the perspective of group blindness prevention and blindness prevention, the World Health Organization degenerates and turbids the lens, becomes opaque, and even affects vision. Those with corrected visual acuity of 0.7 or less are classified into the cataract diagnosis range.
2. Spastic paraplegia refers to the increase of bilateral severe paralytic muscle tension, the patient's lower limbs tonic and adduction, accompanied by compensatory trunk movement, walking effort, scissor-like gait.
Symptom
Symptoms of Pediatric Meow Syndrome Common Symptoms Wide Eyes of Mind Mental retardation High Stenosis Bow Small Head Scoliosis Young Cataract Vascular Malformation Full Moon Face Muscle Tension Reduction and Finger Toe Malformation
The sick child is born with low body weight, the average weight is less than 2500g, the length is lower than the normal child, the average head circumference is 31cm, the growth disorder, the most prominent feature is that the infancy is weak, sad, Mimi like a meow crying, This kind of crying occurs when exhaling, does not appear when inhaling, and its mechanism of production is unknown. Some people think that it may be caused by the weakness of the epiglottic cartilage or the softening of the throat, which leads to the leakage of the throat during exhalation, and some people think that it is related to brain damage. Typical crying often disappears early in childhood, but some older children and adults still have unique cries.
The child's craniofacial dysplasia, the head is small and round, the full moon face, the distance between the eyes is too wide and the small jaw is very obvious, the cleft palate is slightly obliquely downward, there is internal suede, strabismus, cataract, and the nasal bridge is wide and flat. Small ear, slightly lower, sometimes narrow ear canal, with age, small head persists, but face becomes longer, mandibular dysplasia is more obvious, caries, zygomatic arch, 1/3 case can have congenital cardiovascular Malformations, kidney and various skeletal deformities (such as scoliosis, and refers to toe and rib deformities, etc.) can also be seen, the muscles of the limbs are low, the muscle tension increases with age, the reflex is enhanced, and the development is obviously backward. Sitting, when I am 4 years old, I will go away. There is a kind of sloppy gait. Some sick children are like bedridden like baby. They cant talk or can only say a few words. The intelligence is low and the IQ is less than 20.
Examine
Examination of pediatric meow syndrome
1. Analysis of karyotype of peripheral blood cells: A short arm deletion occurs in one of the 5th pair of chromosomes of the patient, but the size of the missing region is different, and the initial site is 5p14-5p15, resulting in the short arm of chromosome 5 being single. Karyotype: 46, XX (XY), 5p-, the type of deletion in children with this syndrome includes simple terminal deletion, intermediate deletion, translocation loss and other types of deletion, occasional chimera or circular karyotype occur.
2. Amniocentesis chromosome examination: amniotic fluid is taken in the second trimester of pregnancy, and the karyotype analysis of the fetus is performed after cell culture. Once the abnormal karyotype is found, the pregnancy can be terminated in time.
3. Fluorescence in situ hybridization: Select probe according to the key region-specific sequence of meow syndrome, and after biotin or digoxigenin labeling, hybridize with the lymphocytes or amniocytes, and pass fluorescein affinity. The display of the signal indicates that there is a 5p deletion and a deletion site. In the normal human cells, the probe hybridization site shows a specific fluorescent signal. If there is no fluorescence signal, the site is missing, which is the diagnosis of the syndrome. Reliable basis.
X-ray films, ultrasound, electrocardiogram, EEG, etc. can be routinely performed. Some children can find congenital heart disease, abnormal EEG changes, X-ray examination can find scoliosis, and refers to toe and rib deformity. .
Diagnosis
Diagnostic identification of pediatric meow syndrome
The diagnosis of meow syndrome is not only based on the clinical phenotype, but also the cytogenetic test. The common karyotype analysis can make a preliminary diagnosis, but because of the difficulty in accurate positioning, it often lacks chromosomal translocation or other special Deletion of the type is not easy to make a definitive diagnosis, and FISH technology should be used for further precise positioning to identify the missing starting site.
Different from other chromosomal aberrations, such as 21-trisomy, 13-trisomy, 8-trisomy, 9-trisomy syndrome, cell chromosome examination can help identify.
21-trisomy syndrome, also known as congenital or Down syndrome, is the most common birth defects caused by autosomal aberrations in children. As the name implies, the disease is a mental disorder with a special phenotype caused by innate factors. The incidence of 21-trisomy syndrome in live births in China is about 0.5-0.6, and the ratio of male to female is 3..2, 60% of children suffer from abortion in the early stage of the fetus. The main clinical features of the child are mental disorders, poor physical development and special facial features, and may be associated with multiple deformities.
