This stage is often overlooked because symptoms of the disorder may be somewhat vague, and parents and doctors may not notice the subtle slowing of development at first. The infant may begin to show less eye contact and have reduced interest in toys. There may be delays in gross motor skills such as sitting or crawling. Hand-wringing and decreasing head growth may occur, but not enough to draw attention.
This stage usually lasts for a few months but can continue for more than a year. Stage II, or the rapid destructive stage, usually begins between ages 1 and 4 and may last for weeks or months.
Its onset may be rapid or gradual as the child loses purposeful hand skills and spoken language. Characteristic hand movements such as wringing, washing, clapping, or tapping, as well as repeatedly moving the hands to the mouth often begin during this stage. The child may hold the hands clasped behind the back or held at the sides, with random touching, grasping, and releasing.
The movements continue while the child is awake but disappear during sleep. Breathing irregularities such as episodes of apnea and hyperventilation may occur, although breathing usually improves during sleep. Some girls also display autistic-like symptoms such as loss of social interaction and communication. Walking may be unsteady and initiating motor movements can be difficult. Slowed head growth is usually noticed during this stage. Stage III, or the plateau or pseudo-stationary stage, usually begins between ages 2 and 10 and can last for years.
Apraxia, motor problems, and seizures are prominent during this stage. However, there may be improvement in behavior, with less irritability, crying, and autistic-like features. A girl in stage III may show more interest in her surroundings and her alertness, attention span, and communication skills may improve. Many girls remain in this stage for most of their lives. Stage IV, or the late motor deterioration stage, can last for years or decades.
Prominent features include reduced mobility, curvature of the spine scoliosis and muscle weakness, rigidity, spasticity, and increased muscle tone with abnormal posturing of an arm, leg, or top part of the body.
Girls who were previously able to walk may stop walking. Cognition, communication, or hand skills generally do not decline in stage IV. Repetitive hand movements may decrease and eye gaze usually improves. Scientists identified the gene — which is believed to control the functions of many other genes — in The MECP2 gene contains instructions for the synthesis of a protein called methyl cytosine binding protein 2 MeCP2 , which is needed for brain development and acts as one of the many biochemical switches that can either increase gene expression or tell other genes when to turn off and stop producing their own unique proteins.
Because the MECP2 gene does not function properly in individuals with Rett syndrome, insufficient amounts or structurally abnormal forms of the protein are produced and can cause other genes to be abnormally expressed.
Scientists have identified mutations in the CDKL5 and FOXG1 genes in individuals who have atypical or congenital Rett syndrome, but they are still learning how those mutations cause the disorder. Scientists believe the remaining cases may be caused by partial gene deletions, mutations in other parts of the MECP2 gene, or additional genes that have not yet been identified, and they continue to look for other causes.
This condition leads to developmental problems in children. It mostly affects language skills and hand use. This gene is on the X chromosome. Females have 2 X chromosomes. Even when one chromosome has this defect, the other X chromosome is normal enough for the child to survive.
Males born with this defective gene do not have a second X chromosome to make up for the problem. Therefore, the defect usually results in miscarriage , stillbirth , or very early death. An infant with RTT usually has normal development for the first 6 to 18 months.
Symptoms range from mild to severe. NOTE: Problems with breathing patterns may be the most upsetting and difficult symptom for parents to watch. Why they happen and what to do about them is not well understood.
Most experts recommend that parents remain calm through an episode of irregular breathing like breath holding. It may help to remind yourself that normal breathing always returns and that your child will become used to the abnormal breathing pattern. Genetic testing may be done to look for the gene defect. But, since the defect is not identified in everyone with the disease, the diagnosis of RTT is based on symptoms. Supplemental feedings can help with slowed growth. A feeding tube may be needed if the child breathes in aspirates food.
A diet high in calories and fat combined with feeding tubes can help increase weight and height. Many studies over the past decade have provided evidence that the vast majority of MECP2 mutations originate in the sperm. Since fathers give an X to their daughters and a Y chromosome to their sons the MECP2 mutation can only be transmitted from father to daughter. This is the reason why Rett is seen primarily in girls. Boys, on the other hand, get their MECP2 mutations from their mother, a situation that arises only rarely.
Mutations can also originate in a single cell as the male embryo is developing. Two types of chromosomes determine the sex of an embryo: the X and the Y chromosomes. Girls have two X chromosomes, and boys have one X and one Y chromosome.
Because the mutated gene that causes Rett syndrome is located on the X chromosome, females have twice the opportunity to develop a mutation in one of their X chromosomes. Females with Rett syndrome usually have one mutated X chromosome and one normal X chromosome.
Only one X chromosome in a given cell remains active throughout life and cells randomly determine which X chromosome will remain active. If the cells have an active mutated gene more often than the normal gene, the symptoms of Rett syndrome will be more severe. This random process allows most females with Rett syndrome to survive infancy. Because most boys have only one X chromosome, when this gene is mutated to cause Rett syndrome the detrimental effects are not softened by the presence of a second, normal X chromosome.
As a result, many males with Rett syndrome are stillborn or do not live past infancy. Duplication of the MECP2 gene can occur in boys and affects intellectual and physical function. Is Rett syndrome passed from one generation to the next? This means that some of the X chromosome genes in a boy's body have the Rett mutation, and some genes do not have the mutation.
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