Three-limbed thumb polysyndactyly syndrome is characterized by multimemberedness of the thumb, often associated with syndactyly and multimemberedness of the toes. The malformation syndrome arises on the basis of a genetic mutation and is inherited in an autosomal dominant manner, with expressivity subject to variability. Patients are treated by surgical amputation.
What is three-limb thumb polysyndactyly syndrome?
Polydactyly is a condition in which the patient suffers from multiple limbs in the fingers or toes. Such multimemberedness also characterizes, in terms of leading symptoms, the three-limb thumb polysyndactyly syndrome. This complex of symptoms is an extremely rare birth defect that is sometimes classified among the malformation syndromes. The complex also goes by the name three-limbed thumb polysyndactyly syndrome postaxial polydactyly type 2. The malformation syndrome affects the feet in addition to the hands and is characterized primarily by a finger-like three-limbed thumb that may be associated with facultative duplication of the thumb elements. Holt-Oram syndrome has similar malformations and is associated with tripartite thumb polysyndactyly syndrome as is Fanconi anemia. The prevalence for the syndrome is reported to be approximately one case per 1,000,000 people. Familial clusters have been observed in the cases documented to date. Therefore, science assumes heritability of the malformation complex. The mode of inheritance is reported to be autosomal dominant inheritance with penetrance and a variable expressivity.
Causes
Three-limb thumb polysyndactyly syndrome has genetic causes. A mutation is associated with the malformation syndrome. Thus, mutations in the LMBR1 gene are thought to underlie the disorder. This gene is located in gene locus 7q36.3 and codes in DNA for a protein called Limb region 1 protein homolog. Whether the protein is directly involved in limb development is as yet unclear. However, the protein shows abnormal activity following a mutation of the coding gene, presumably causing the symptoms of three-limb thumb polysyndactyly syndrome. The exact relationship between the gene defect and its individual consequences has not been conclusively investigated. It is also not yet known whether external factors contribute to the development of the syndrome in addition to genetic factors. If there is no familial clustering of the syndrome in a family, a new mutation of the gene can presumably still occur, leading to sporadic tripartite thumb polysyndactyly syndrome.
Symptoms, complaints, and signs
Patients with three-limb thumb polydactyly syndrome suffer from abnormalities of the hands and, at times, feet. They are affected by polydactyly, which manifests preferentially in the thumb area. The thumb of the patients is multi-limb, so mainly tripartite. The thumb function is usually preserved. The multi-limb nature of the thumb has a finger-like appearance. In some cases, syndactyly of the fingers or toes is present in addition to the multimemberedness. This is always referred to when the limbs of the hand or foot are fused together. Just as poly- and syndactyly of the hand manifest themselves preferentially on the thumb, they find manifestation on the feet of the patients preferentially on the big toe. In most patients, the changes in the foot are much less pronounced. In some they are barely visible and in others they are not present at all. Even within the same family, the extent of malformations can vary widely.
Diagnosis
The diagnosis of three-limb thumb polysyndactyly syndrome is made by the clinical presentation of the patient. Since no other malformations are present apart from the aforementioned malformations, the differential diagnostic differentiation from other malformation syndromes is rather easy during the diagnostic process. There is a risk of confusion of the three-limbed thumb polysyndactyly syndrome almost exclusively with the Holt-Oram syndrome. In case of doubt, differentiation can be made by molecular genetic analysis. The prognosis of the patients is excellent. On the one hand, the malformations usually do not impair the function of the limbs of the hand and foot, and on the other hand, they can be excellently corrected in most cases.Because no other malformations are present except for the anomalies of the toes and fingers, the three-limb thumb polysyndactyly syndrome is one of the most prognostically favorable malformation syndromes of all.
Complications
Three-limb thumb polysyndactyly syndrome causes severe abnormalities and malformations of the feet and hands in most cases. The functions of the individual fingers and toes are usually preserved, although the syndrome may continue to restrict the patient’s daily life. In many cases, many activities are only possible to a limited extent or are associated with complications. Children in particular may experience teasing and bullying due to the three-limbed thumb polysyndactyly syndrome. As a result, children develop depression or other psychological symptoms and suffer from a reduced quality of life. Not all patients are affected by changes in the hands and feet, so they can occur on only one of the extremities. It is usually not possible to treat the three-limb thumb polysyndactyly syndrome causally. For this reason, only amputation of the respective limb is possible if desired by the patient. In many cases, the symptoms are not corrected if they do not lead to restrictions in the patient’s life. However, most of the patients complain about the aesthetic aspects, which can lead to psychological discomfort. In the case of amputation, there are no further complications or discomfort.
When should one go to the doctor?
If there is an accumulation of the syndrome in the family, an examination should be performed during pregnancy. Expectant parents are best to contact the responsible physician in case of corresponding risk factors and make an appointment for an ultrasound examination. The condition is usually detected after birth at the latest and can then be treated specifically. In case of chronic pain and other complications, a doctor should be consulted. If an accident or fall occurs as a result of a malposition, the emergency services must be called in any case. Medical correction of the deformity is absolutely necessary. Accompanying physiotherapeutic support is also recommended under certain circumstances. Since those affected often develop inferiority complexes and other psychological suffering later in life, a psychologist should be consulted. However, only the responsible physician can answer in detail what measures should be taken. In addition to the family doctor, a specialist in malformations or a specialist in the particular symptom may be consulted.
Treatment and therapy
For patients with three-limb thumb polysyndactyly syndrome, there is no causative therapy available in the strict sense, since the cause is a genetic mutation. The abnormalities are therefore not treated causally, but symptomatically. Thus, the treatment depends strongly on the symptoms in the individual case. In most cases, the malformations are not initially corrected in the first period after birth. This is especially true in the case of additionally present syndactyls, which are all the more difficult to correct the smaller the hands and feet of the affected person. Since polydactyls do not impair the function of the hand or foot, surgical correction is not mandatory from a medical point of view. Syndactyls, however, can impair function. Surgical separation procedures are available for correction, which are usually crowned with success after a certain age, especially in the case of membranous syndactyls. Amputation of the multiple limbs in polydactyly can also make sense from a certain age, since the affected child may encounter rejection or even discrimination at school at the latest. If this connection proves to be true, serious psychological problems may develop in the course of life. To avoid such a course, surgical amputation makes perfect sense.
Outlook and prognosis
In three-limb thumb polysyndactyly syndrome, self-healing does not occur. For this reason, patients are always dependent on treatment for the condition to provide permanent relief. If treatment does not occur, various changes occur in the patient’s feet. The big toes are mainly affected, although in rare cases the thumbs on the fingers can also be affected.Difficulties in everyday life occur, which have a very negative impact on the patient’s quality of life and restrict everyday life. Children may also suffer from bullying or teasing as a result, causing psychological upset or even depression. Treatment of the three-limb thumb polysyndactyly syndrome is always performed in the form of amputation. This does not result in any further complications or discomfort, with the symptoms being completely relieved as a result. Likewise, this does not negatively affect the function of the hand or foot. The syndrome also does not reduce the patient’s life expectancy. In this regard, early treatment in childhood can directly prevent possible psychological complaints or depression.
Prevention
Three-limb thumb polysyndactyly syndrome cannot be prevented in a narrow sense, as it is a genetic disorder. In the broadest sense, genetic counseling at the pregnancy planning stage can be described as a preventive measure.
Follow-up
In three-limb thumb polysyndactyly syndrome, the measures and options for aftercare are very limited. Because it is a congenital and hereditary condition, complete or causal treatment is usually not possible. Those affected are therefore dependent on purely symptomatic treatment, the main focus being on early detection of the disease. The earlier the three-limbed thumb polysyndactyly syndrome is detected, the better the further course of this disease usually is. If the patient wishes to have children, hereditary counseling can also be performed. This may prevent the syndrome from being passed on to the children. The treatment itself is carried out by surgical interventions and by various therapies. In many cases, exercises from these therapies can be performed in the patient’s own home, which accelerates the healing process. After the procedure, bed rest must be observed in any case. The patient should rest and take care of his or her body. Care and support from relatives and friends is also very important and can contribute to accelerated healing. Whether the three-limb thumb polysyndactyly syndrome reduces the life expectancy of the affected person cannot be universally predicted.
Here’s what you can do yourself
The self-help options for trifid thumb polysyndactyly syndrome are limited. It is not possible to achieve a change in the physical conditions by one’s own means. In everyday life, the focus is on how to deal with the deformity. Children who are born with the genetic disorder should be informed as early as possible about the changes in their body compared to the physique of healthy people. An open approach to the normality of being different helps the child in contact with fellow human beings and playmates of the same age. The child’s self-confidence should be supported and encouraged. In case of emotional or mental problems, the child needs help. In most cases, the assistance of family members or family members who are also ill is sufficient. Together they can practice the challenges of everyday life. The child now meets the environment prepared and learns to assert himself in unpleasant situations. At the same time, the visual changes should not be too much the focus of everyday events. The child’s strengths should be encouraged and the joy of life discovered. With the three-limbed thumb polysyndactyly syndrome the child can live without complaints. It is a visual defect that does not result in a life restriction or threat.
