Ahad, 13 Jun 2010

SINDROM EDWARD

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Definition

Edwards' syndrome is caused by an extra (third) copy of chromosome 18. The extra chromosome is lethal for most babies born with this condition. It causes major physical abnormalities and severe mental retardation. Very few children afflicted with this syndrome survive beyond the first year.

Description

Edwards' syndrome is associated with the presence of a third copy of chromosome number 18. Humans normally have 23 pairs of chromosomes. Chromosomes are numbered 1–22, and the 23rd pair is composed of the sex chromosomes, X and Y. A person inherits one set of 23 chromosomes from each parent. Occasionally, a genetic error occurs during egg or sperm cell formation. A child conceived with such an egg or sperm cell may inherit an incorrect number of chromosomes. In the case of Edwards' syndrome, the child inherits three (trisomy), rather than two, copies of chromosome 18. Ninety-five percent of the children are full trisomies, 2 percent are due to translocations, where only part of an extra chromosome is present (this may be hereditary), while 3 percent are mosaic trisomies, where the extra chromosome is present in some but not all of the cells.

Edwards' syndrome is usually fatal, with most babies dying before birth. Of those who do make it to birth, 20–30 percent die within one month. However, a small number of babies (less than 10 percent) live at least one year.

Edwards' syndrome is also referred to as trisomy 18, trisomy E, and trisomy 16–18. It is the second most common trisomy, after trisomy 21 (Down syndrome).

Demographics

Edwards' syndrome occurs in approximately one in every 5,000 live births and one in every 5,000 stillborn births; it affects girls more often than boys. Women older than their early thirties have a greater risk of conceiving a child with Edwards' syndrome, but it can also occur with younger mothers.

Causes and Symptoms

Most children born with Edwards' syndrome appear weak and fragile, and they are often underweight. The head is unusually small and the back of the head is prominent. The ears are malformed and low-set, and the mouth and jaw are small (micrognathia). The baby may also have a cleft lip or cleft palate. Frequently, the hands are clenched into fists, and the index finger overlaps the other fingers. The child may have clubfeet, and toes may be webbed or fused.

Numerous problems involving the internal organs may be present. Abnormalities often occur in the lungs and diaphragm (the muscle that controls breathing), and blood vessel malformations are common. Various types of congenital heart disease, including ventricular septal defect (VSD), atrial septic defect (ASD), or PDA (patent ductus arteriosus), may be present. The child may have an umbilical or inguinal hernia, malformed kidneys, and abnormalities of the urogenital system, including undescended testicles in a male child (cryptochordism).

When to Call the Doctor

A child with Edwards' syndrome is likely to have many medical and development needs. Parents should develop good working relationships with their doctor, other specialists, and therapists, and should consult them as needed.

If a woman gives birth to a child with Edwards' syndrome and plans to have another child, a doctor as well as a genetic counselor should be consulted so that prenatal screening and genetic counseling can be conducted.

Diagnosis

Edwards' syndrome at birth may be diagnosed by the physical abnormalities characteristic to the syndrome. Physical examination of the infant may show arched type finger print patterns, while x rays may reveal a short breast bone (sternum). Definitive diagnosis is achieved through karyotyping, which involves drawing the baby's blood for a microscopic examination of the chromosomes. Using special stains and microscopy, individual chromosomes are identified, and the presence of an extra chromosome 18 is revealed.

Edwards' syndrome can be detected before birth. If a pregnant woman is older than 35, has a family history of genetic abnormalities, has previously conceived a child with a genetic abnormality, or has suffered earlier miscarriages, she may undergo tests to determine whether her child carries genetic abnormalities. Potential tests include maternal serum alpha-fetal protein analysis or screening, ultrasonography, amniocentesis, and chorionic villus sampling.

In addition, a pregnant woman carrying a child with Edwards' syndrome may have an unusually large uterus during pregnancy, due to the presence of extra amniotic fluid (polyhydramnios). An unusually small placenta may be noted during the birth of the child.

Treatment

There is no cure for Edwards' syndrome. Since babies with Edwards' syndrome frequently have major physical abnormalities, doctors and parents face difficult choices regarding treatment. Abnormalities can be treated to a certain degree with surgery, but extreme invasive procedures may not be in the best interests of an infant whose lifespan is measured in days or weeks. Medical therapy often consists of supportive care with the goal of making the infant comfortable, rather than prolonging life.

However, 5–10 percent of children with Edwards' syndrome do survive past the first year of life, and require appropriate treatment for the many chronic effects associated with the syndrome. Problems with muscle tone and nervous system abnormalities will affect the development of motor skills, possibly resulting in scoliosis (curvature of the spine) and esotropia (crossed eyes). Surgical interventions may be limited by child's cardiac health.

Constipation due to poor abdominal muscle tone is often a life-long problem for babies and children with Edwards' syndrome, resulting in fretfulness, discomfort, and feeding problems. Anti-gas medication, special milk formulas, stool softener medicines, laxatives, and suppositories are all possible treatments that the doctor may recommend to ease the discomfort of gas in the bowels or constipation. An enema should not given to the baby or child because it can deplete electrolytes and alter body fluid composition.

Children with Edwards' syndrome will exhibit severe developmental delays, but with early intervention through special education and therapy programs, they can attain some developmental milestones.

Children with Edwards' syndrome appear to have increased risk of developing a Wilms' tumor, a cancer of the kidney that primarily affects children. Therefore, it is recommended that older infants and children with Edwards' syndrome have a routine ultrasound of the abdominal cavity.

Other illnesses that may affect a child with Edwards' syndrome and that may require treatment include congenital heart disease, pulmonary hypertension, elevated blood pressure, apnea episodes, pneumonias, sinus infections, seizures, urinary tract infections, ear infections, and eye infections. Other abnormalities that may require consideration of medical or surgical intervention include club foot, facial clefts, spina bifida, and hydrocephalus.

Nutritional Concerns

Babies with Edwards' syndrome generally have feeding problems related to difficulties in coordination of breathing, sucking, and swallowing. Many have a weak suck and uncoordinated swallow resulting in choking and sometimes vomiting. Gastroesophageal reflux disease, or GERD (the upward movement of small amounts of stomach contents to the esophagus or throat), aspiration (inhalation or trickle of fluids into the lungs), and oral facial clefts may also contribute to feeding difficulties. The baby should be referred to a feeding specialist to help with feeding problems. The specialist can show the parents how to position the baby's head up, in good body alignment, because a baby with Edwards' syndrome may have hyperextension of the head. This is a common condition that occurs before the baby has developed head control. It results in the elongation of throat muscles, making swallowing more difficult. Because of feeding difficulties, many babies with Edwards' syndrome are fed through a tube inserted through the nose or mouth, down through the esophagus, and into the stomach. Some babies eventually progress to bottle or breastfeeding, while others have a gastrostomy (G-tube) placed abdominally to prevent the trauma of tube insertion. Some children are fed both orally and through the tube.

The baby should be fed with pre-softened preemie nipples and given small amounts frequently. To help prevent reflux, the baby's head should be elevated about 30 degrees or more during feeding and for one to two hours after a feeding. If tolerated, high calories formulas or supplements may be fed to help the baby gain weight.

Prognosis

Most children born with Edwards' syndrome die within their first year of life. The average lifespan is less than two months for 50 percent of the children, and 90–95 percent die before their first birthday. The 5–10 percent of children who survive their first year have severe developmental disabilities. They need support to walk, and learning is limited. Verbal communication is also limited, but they can respond to comforting and can learn to recognize, smile, and interact with caregivers and others, and acquire such skills as rolling over and self-feeding. They will have many physical abnormalities that require constant care as doctors and parents work together to prevent and treat various problems.

Prevention

Most cases of Edwards' syndrome are not hereditary and cannot be prevented. However, parents who have had a child with Edwards' syndrome are at increased risk of having another child with the syndrome.

Parental Concerns

Following the birth of a child with Edwards' syndrome, families may wish to seek counseling regarding the effects on relationships within the family. Many people respond with guilt, fear, or blame when a genetic disorder is manifested within a family. Support groups are good sources of information about Edwards' syndrome and can offer emotional and psychological support.

For those families whose child does survive the first weeks of life, the doctor should review with the parents the expected clinical course of the condition, and prepare a management plan for use when the child goes home. Each case must be considered on an individual basis, and the doctor should acknowledge the personal feelings of the parents, as well as the individual circumstances of each child. The theme of "best interest of the child" helps as a guiding principle in decision-making throughout the life of the child. There will be many challenges associated with the care of a child with Edwards' syndrome. As medical crises occur, parents will face decisions and emotions related to the possibility of the child dying.

See also Atrial septal defect; Congenital heart disease.

Resources

Books

Barnes, Ann M., and John C. Carey. Care of the Infant and Child with Trisomy 18 and 13: Medical Problems, Reported Treatments, and Milestones. Omaha, NE: Munroes-Meyer Institute for Genetics and Rehabilitation, 2000.

Stenson, Carol M., et al. Trisomy 18: A Guidebook for Families. Omaha, NE: Munroes-Meyer Institute for Genetics and Rehabilitation, 2000.

Organizations

Chromosome 18 Registry & Research Society. 7715 Oakridge Drive, San Antonio, TX 78229. (210) 657-4968. Web site: www.chromosome18.org.

Support Organization for Trisomy 18, 13, and Related Disorders (SOFT). 2982 South Union St., Rochester, NY 14624. (800) 716-7638. Web site: www.trisomy.org.

Web Sites

Trisomy 18 Support: Families Caring for Families. Available online at: www.trisomy18support.org.

[Article by: Judith Sims; Julia Barrett]

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Rabu, 2007 Jun 13

Bimbang Sindrom Edward Berulang

SOALAN:
SAYA berusia 30 tahun dan ibu tiga orang anak. Dua anak pertama dilahirkan secara normal.

Anak ketiga dilahirkan secara pembedahan dan disahkan menghidap Sindrom Edward sejurus selepas dilahirkan (pada Disember 2006) tetapi bayi itu meninggal dunia selepas 31 hari dilahirkan.

Berapa lama tempoh sesuai untuk saya hamil kembali? Apakah jenis rawatan yang patut diikuti sebelum hamil untuk mengelak perkara sama berulang?

Apakah kemungkinan kandungan berikutnya mengalami sindrom yang sama?

Hanis,
Kuala Lumpur

JAWAPAN:
SINDROM Edward ialah sejenis ketidaknormalan kromosom. Ia adalah penghasilan satu lagi kromosom pada kromosom ke-18 (daripada dua sahaja menjadi tiga), maka ia juga disebut Trisomy 18. Sindrom Edward ialah trisomi kedua paling kerap ditemui selepas Trisomy 21 (juga dinamakan sindrom Down).

Selain itu ada juga Trisomy 13 (sindrom Patau), manakala ketidaknormalan kromosom yang lain kebanyakannya berakhir dengan keguguran awal. Sindrom Edward berlaku dalam 1:3000 kehamilan atau 1:6000 kelahiran hidup di mana 80 peratus kes membabitkan bayi perempuan (tiga kali ganda membabitkan bayi perempuan berbanding lelaki).

Setiap orang mempunyai 46 kromosom (23 pasang kromosom) dalam setiap sel tubuhnya. Mempunyai lebihan kromosom pada kromosom 18 (trisomi 18) bermakna seseorang bayi itu mempunyai lebihan maklumat pada setiap selnya (berjumlah 47 kromosom).

Ini memberi kesan kepada pertumbuhannya sehingga menyebabkan gangguan kepada pembentukan organ seperti:

- Ketidaknormalan jantung, sistem pernafasan dan buah pinggang

- Bentuk kepala seperti menonjol pada bahagian belakang, mulut dan dagu bersaiz kecil, kedudukan telinga lebih rendah, jarak antara mata yang luas dan kelopak mata atas yang menurun.

- Ketidaknormalan tulang n Susunan tulang jari tangan dan kaki

- Gangguan pembesaran tubuh dan gangguan perkembangan mental

Berbeza dengan sindrom Down, sindrom Edward lazimnya tidak bertahan lama. Separuh kes berakhir dengan keguguran atau kematian dalam kandungan.

Bayi yang lahir hidup pula tidak dapat bertahan lama, 50 peratus daripadanya meninggal dalam tempoh dua bulan kelahiran dan angka ini meningkat kepada 90 peratus sebelum bayi mencapai usia setahun, kebanyakannya disebabkan masalah pernafasan dan ketidaknormalan jantung.

Secara amnya, dalam setiap kandungan seterusnya, risiko untuk sindrom Edward kurang daripada satu peratus.

Maklumat kromosom bayi anda dahulunya amat penting diketahui untuk mengetahui risiko sindrom Edward berulang:

- Trisomi 18 sebenar (non-disjunction meiosis) berlaku dalam 90 peratus kes namun risiko berulang rendah (hanya kurang daripada satu peratus).

- Trisomi 18 mosaik (non-disjunction mitosis) berlaku dalam 10 peratus kes, risiko berulang lebih rendah.

- Kromosom 18 translokasi jarang berlaku namun risiko berulang paling tinggi kerana ia boleh bersifat keturunan. Anda dan suami seeloknya turut menjalani ujian kromosom jika bayi dahulu mempunyai translokasi Trisomi 18.

Selain itu, peningkatan usia wanita juga memberikan risiko ketidaknormalan kromosom yang lebih tinggi seperti sindrom Edward dan sindrom Down.

Setakat ini, sindrom Edward belum boleh dicegah atau dirawat. Tiada kaedah atau petua untuk mencegahnya daripada berlaku. Ujian yang ada hanyalah untuk mengesan kehadirannya pada embrio atau janin atau bayi.

Bergantung kepada jenis ujian, ia hanya boleh dikesan selepas pembentukan embrio sama ada pada peringkat embrio, janin atau selepas lahir.

Sekiranya bayi dahulu mempunyai translokasi kromosom 18, seeloknya anda menjalani mana-mana ujian di bawah.

- CVS (chorionic villous sampling) dilakukan pada sekitar 10 hingga 12 minggu kehamilan secara mengambil sampel daripada uri. Jarum panjang akan dimasukkan melalui kulit abdomen, menembusi rahim sehingga kepada uri.

Sel uri ini akan dilakukan ujian kromosom. Risiko keguguran akibat prosedur ini sekitar dua peratus.

- Amniocentesis dilakukan sekitar 14 hingga 18 minggu kehamilan secara mengambil sampel air ketuban menggunakan jarum panjang yang ditusuk melalui kulit abdomen menembusi rahim. Sel bayi yang menggelupas dan terapung di dalam air ketuban ini akan diuji ujian kromosom. Risiko keguguran sekitar satu peratus.

- Jika menggunakan teknik persenyawaan tabung uji, sel pada embrio yang terbentuk akan diambil untuk ujian kromosom melalui kaedah PGD (Pre-implantation genetic diagnosis). Harus diingat, tidak semua ujian ketidaknormalan janin dilakukan, ia lebih bergantung kepada bahan uji yang tersedia.

Lebih mudah lagi untuk menjalani ujian saringan (tidak tepat keputusannya) namun ia hanya membantu dan bukanlah bersifat diagnostik:

Memandangkan anda sudah bersalin secara pembedahan, lazimnya tempoh dua hingga tiga tahun digalakkan sebelum anda hamil lagi.

Keutuhan dinding rahim anda kini tidak seperti wanita yang tidak pernah menjalani pembedahan Caesarean, anda juga mempunyai risiko yang lebih tinggi untuk keadaan yang dinamakan ‘parut merekah’ atau ‘rahim pecah’ (scar dehiscence atau uterine rupture) ketika kehamilan trimester ketiga atau ketika sakit bersalin kelak.


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