| Sirenomelia | |
|---|---|
 | |
| Sirenomelia, Lyon natural history and anatomy museum | |
| Specialty | Medical genetics  |
| Symptoms | Fused legs |
| Complications | Malformations of organs |
| Usual onset | Birth |
| Causes | See Causes |
| Risk factors | ? |
| Treatment | Surgery |
| Prognosis | Usually die in infancy |
| Deaths | ? |
Sirenomelia, also called mermaid syndrome, is a rare congenital deformity in which the legs are fused together, giving the appearance of a mermaid's tail, hence the nickname.
Sirenomelia is classified by the skeletal structure of the lower limb, ranging from class I, where all bones are present and only the soft tissues are fused, to class VII where the only bone present is a fused femur. [1]
It has also been classified as an expanded part of the VACTERL association and as a form of caudal regression syndrome. [1] [2] [3]
Sirenomelia is mainly characterized by the fusion of both legs with rotation of the fibula. It may include the absence of the lower spine, as well as abnormalities of the pelvis and renal organs. It was previously thought to be a severe form of sacral agensis/caudal regression syndrome, but more recent research confirms that these two conditions are not related. [4] In general, the more severe cases of limb fusion correlate with more severe dysplasia in the pelvis. Rather than the two iliac arteries present in fetuses with complete renal agenesis, fetuses with sirenomelia display no branching of the abdominal aorta, which is always absent. [1]
Associated defects recorded in cases of sirenomelia include neural tube defects (rachischisis, anencephaly, and spina bifida), holoprosencephaly, hypoplastic left heart syndrome, other heart defects, esophageal atresia, omphalocele, intestinal malrotation, persistent cloaca, and other limb defects (most commonly absence of the radius). [1]
The ultimate cause of sirenomelia is a subject of debate. The first hypothesis of its origin was developed in 1927 and proposed that a lack of blood supply to the lower limbs during their development is responsible for the defect. This "vascular steal" hypothesis was developed in response to the observed absence or severe underdevelopment of the aorta below the umbilical artery, which "steals" the blood supply from the lower limbs. Other hypotheses involve an insult to the embryo between 28 and 32 days affecting the caudal mesoderm, a teratogen exposure affecting the neural tube during neurulation, and a defect in the twinning process that either stops the process of caudal differentiation or generates a second primitive streak. [1]
Maternal diabetes mellitus has been associated with caudal regression syndrome and sirenomelia, [5] [6] although a few sources question this association. [7] Prenatal cocaine exposure has also been suggested as an association with sirenomelia. [1]
In animal models, several genes have been found to cause or be associated with sirenomelia. The srn (siren) gene is observed to cause hindlimb fusion in homozygous mice. [1] [8] Mice with knockouts or mutations in both tsg1 and bmp7 will also have hindlimb fusion. [1] [9] [10]
Though obvious at birth, sirenomelia can be diagnosed as early as 14 weeks gestation on prenatal ultrasound. When there is low amniotic fluid around the fetus (oligohydramnios), the diagnosis is more difficult. [1]
Sirenomelia is usually fatal. Many pregnancies with a sirenomelic fetus spontaneously miscarry. One-third to one-half of infants are stillborn, with all but a few dying in the neonatal period. [1]
In cases of monoamniotic twins where one is affected, the twin with sirenomelia is protected from Potter sequence (particularly pulmonary hypoplasia and abnormal facies) by the normal twin's production of amniotic fluid. [11] [1]
This condition is found in approximately one out of every 100,000 live births; studies produce rates from 1 in 68,741 to 1 in 97,807. [1] [12] It is 100 to 150 times more likely in identical (monozygotic) twins than in singletons or fraternal twins. [11] [1] Sirenomelia is not associated with any ethnic background, but fetuses with sirenomelia are more likely to be male. [1]
The word sirenomelia derives from the ancient Greek word seirēn, referring to the mythological Sirens, who were sometimes depicted as mermaids, and melos, meaning "limb".
Sirenomelia was first reported in 1542. In 1927, Otto Kampmeier discovered the association between sirenomelia and single umbilical artery. [1]
Only a few individuals who had some functioning kidney tissues have survived the neonatal period. [1]
Tiffany Yorks of Clearwater, Florida (May 7, 1988 – February 24, 2016) [13] underwent successful surgery in order to separate her legs before she was a year old. She was the longest-surviving sirenomelia patient to date. She had mobility issues due to her fragile leg bones and compensated by using crutches or a wheelchair. She died on February 24, 2016, at the age of 27.[ citation needed ]
Shiloh Jade Pepin (August 4, 1999 – October 23, 2009) was born in Kennebunkport, Maine, United States with her lower extremities fused, no bladder, no uterus, no rectum, only 6 inches of large intestine, no vagina, only one quarter of a kidney and one ovary. Her parents initially anticipated she could expect only a few months of life. At age 4 months, her natural kidney failed, and she began dialysis. [14] A kidney transplant at age 2 lasted a number of years, and in 2007 a second kidney transplant was successful. She attended Consolidated Elementary School. She remained hopeful about her disease and joked often and lived her life happily, despite her challenges, as seen in her TLC documentary in "Extraordinary People: Mermaid Girl". Shiloh and her family were debating surgery because of the risks involved, even though it would improve her quality of life. Many people who have this condition undergo surgery when they are young, but Shiloh was already 8 years old in the documentary and had not undergone surgery. Shiloh was the only one of the three survivors of sirenomelia without surgery for separation of the conjoined legs. [15] She died of pneumonia on October 23, 2009, at Maine Medical Center in Portland, Maine, at the age of 10; [16] having appeared on the Oprah Winfrey Show on September 22, 2009. [17] Shiloh gained a following of admirers by documenting her condition on TV, Facebook, and the Internet.
Milagros Cerrón Arauco (April 27, 2004 – October 24, 2019) was born in Huancayo, Peru. Although most of Milagros' internal organs, including her heart and lungs, were in perfect condition, she was born with serious internal defects, including a deformed left kidney and a very small right one located very low in her body. In addition, her digestive, urinary tracts and genitals shared a single tube. This birth defect occurs during the gastrulation week (week 3) of embryonic development. Gastrulation establishes the three germ layers: ectoderm, mesoderm and endoderm. It seems that complications such as defects in the urogenital system as mentioned above can be possibly due to malformations in the intermediate mesoderm.
A four-hour operation to insert silicone bags between her legs to stretch the skin was successfully completed on February 8, 2005. A successful operation to separate her legs to just above the knee took place May 31, 2005, in a "Solidarity Hospital" in the district of Surquillo in Lima. The procedure, however, was so intensive that she became traumatized to the degree of losing her ability to form proper speech patterns, leaving her nearly mute. It is not known if this was a physiological or psychological condition. However, at Milagros' second birthday, her mother reported that she knew more than 50 words. A second operation to complete the separation up to the groin took place on September 7, 2006. [18]
Her doctor Luis Rubio said he was pleased with the progress Milagros had made, but cautioned that she still needed 10 to 15 years of rehabilitation and more operations before she could lead a normal life, particularly reconstructive surgery to rebuild her rudimentary anus, urethra and genitalia.
Milagros' parents are from a poor village in Peru's Andes Mountains; the Solidarity Hospital had given a job to her father Ricardo Cerrón so that the family could remain in Lima, while the City of Lima pledged to pay for many of the operations. [19]
Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology caused by teratogens. Teratogens are substances that may cause non-heritable birth defects via a toxic effect on an embryo or fetus. Defects include malformations, disruptions, deformations, and dysplasia that may cause stunted growth, delayed mental development, or other congenital disorders that lack structural malformations. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental insult. The extent to which teratogens will impact an embryo is dependent on several factors, such as how long the embryo has been exposed, the stage of development the embryo was in when exposed, the genetic makeup of the embryo, and the transfer rate of the teratogen.
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders.
A deformity, dysmorphism, or dysmorphic feature is a major abnormality of an organism that makes a part of the body appear or function differently than how it is supposed to.
Twin-to-twin transfusion syndrome (TTTS), also known as feto-fetal transfusion syndrome (FFTS), twin oligohydramnios-polyhydramnios sequence (TOPS) and stuck twin syndrome, is a complication of monochorionic multiple pregnancies in which there is disproportionate blood supply between the fetuses. This leads to unequal levels of amniotic fluid between each fetus and usually leads to death of the undersupplied twin and, without treatment, usually death or a range of birth defects or disabilities for a surviving twin, such as underdeveloped, damaged or missing limbs, digits or organs, especially cerebral palsy.
Potter sequence is the atypical physical appearance of a baby due to oligohydramnios experienced when in the uterus. It includes clubbed feet, pulmonary hypoplasia and cranial anomalies related to the oligohydramnios. Oligohydramnios is the decrease in amniotic fluid volume sufficient to cause deformations in morphogenesis of the baby.
Pediatric surgery is a subspecialty of surgery involving the surgery of fetuses, infants, children, adolescents, and young adults.
An imperforate anus or anorectal malformations (ARMs) are birth defects in which the rectum is malformed. ARMs are a spectrum of different congenital anomalies which vary from fairly minor lesions to complex anomalies. The cause of ARMs is unknown; the genetic basis of these anomalies is very complex because of their anatomical variability. In 8% of patients, genetic factors are clearly associated with ARMs. Anorectal malformation in Currarino syndrome represents the only association for which the gene HLXB9 has been identified.
The VACTERL association refers to a recognized group of birth defects which tend to co-occur. This pattern is a recognized association, as opposed to a syndrome, because there is no known pathogenetic cause to explain the grouped incidence.
Vaginal atresia is a condition in which the vagina is abnormally closed or absent. The main causes can either be complete vaginal hypoplasia, or a vaginal obstruction, often caused by an imperforate hymen or, less commonly, a transverse vaginal septum. It results in uterovaginal outflow tract obstruction. This condition does not usually occur by itself within an individual, but coupled with other developmental disorders within the female. The disorders that are usually coupled with a female who has vaginal atresia are Mayer-Rokitansky-Küster-Hauser syndrome, Bardet-Biedl syndrome, or Fraser syndrome. One out of every 5,000 women have this abnormality.
Caudal regression syndrome, or sacral agenesis, is a rare birth defect. It is a congenital disorder in which the fetal development of the lower spine—the caudal partition of the spine—is abnormal. It occurs at a rate of approximately one per 60,000 live births.
Fetal surgery also known as antenatal surgery, prenatal surgery, is a growing branch of maternal-fetal medicine that covers any of a broad range of surgical techniques that are used to treat congenital abnormalities in fetuses who are still in the pregnant uterus. There are three main types: open fetal surgery, which involves completely opening the uterus to operate on the fetus; minimally invasive fetoscopic surgery, which uses small incisions and is guided by fetoscopy and sonography; and percutaneous fetal therapy, which involves placing a catheter under continuous ultrasound guidance.
Body Shock is a British medical documentary series about the conditions or lives of extraordinary people. It was originally produced by redback for Channel 4 in the UK, but in September 2006, it was taken over by ArkMedia.
Intermediate mesoderm or intermediate mesenchyme is a narrow section of the mesoderm located between the paraxial mesoderm and the lateral plate of the developing embryo. The intermediate mesoderm develops into vital parts of the urogenital system.
Extraordinary People is a television documentary series broadcast on Channel 5 in the United Kingdom. Each programme follows the lives of people with a rare medical condition and/or unusual ability. People featured have or had rare illnesses such as rabies and eye cancer. Many of these people do activities previously thought impossible for people in their condition.
Congenital amputation is birth without a limb or limbs, or without a part of a limb or limbs.
Roberts syndrome, or sometimes called pseudothalidomide syndrome, is an extremely rare autosomal recessive genetic disorder that is characterized by mild to severe prenatal retardation or disruption of cell division, leading to malformation of the bones in the skull, face, arms, and legs.
Constriction ring syndrome (CRS) is a congenital disorder with unknown cause. Because of the unknown cause there are many different, and sometimes incorrect names. It is a malformation due to intrauterine bands or rings that give deep grooves in, most commonly, distal extremities like fingers and toes. In rare cases the constriction ring can form around other parts of the fetus and cause amputation or even intrauterine death. The anatomy proximal to the site of constriction is developmentally normal. CRS can be associated with other malformations with club foot being most common. The precise configuration of the bands, lymphedema, and character of the amputations are not predictable and vary with each individual patient. Also, more than one extremity is usually affected, and it is rare for only one ring to present as an isolated malformation with no other manifestation of this syndrome.
Caudal duplication, is a rare congenital disorder in which various structures of the caudal region, embryonic cloaca, and neural tube exhibit a spectrum of abnormalities such as duplication and malformations. The exact causes of the condition is unknown, though there are several theories implicating abnormal embryological development as a cause for the condition. Diagnosis is often made during prenatal development of the second trimester through anomaly scans or immediately after birth. However, rare cases of adulthood diagnosis has also been observed. Treatment is often required to correct such abnormalities according to the range of symptoms present, whilst treatment options vary from conservative expectant management to resection of caudal tissue to restore normal function or appearance. As a rare congenital disorder, the prevalence at birth is less than 1 per 100,000 with less than 100 cases reported worldwide.
A lipomyelomeningocele is a type of closed neural tube defect that affects around 3 to 6 babies out of 100,000 births. It is an example of a spinal lipoma, which is a collection of adipose tissue, or fat, that is located at or around the spinal cord. Essentially, it is a tumor of fat located on the spinal cord. A lipomyelomeningocele defect is present at birth and can present with physical defect of the spine and back, and it can also cause various neurological symptoms such as weakness and bladder and bowel incontinence. The general treatment for this spinal defect is surgical detachment of the lipoma from the spine.
{{cite book}}: CS1 maint: multiple names: authors list (link){{cite book}}: CS1 maint: multiple names: authors list (link){{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)In Memoriam: The Oprah Show has hosted a number of unforgettable guests over the years. Look back at some of those who are no longer with us.