Polydactyly - a congenital abnormality of the fingers, which is reflected in the increase in their number. Most often it is seen on the hands, but may affect the fingers and toes, or both upper and lower limbs.
Typically, this anatomical defect is inherited as a dominant trait polydactyly at one of the parents. It is not life-threatening, but can cause psychological trauma, disrupt the function of limbs and slow physical growth and limit the choice of a profession in the future.
According to statistics, polydactyly occurs with equal frequency in boys and girls. According to various reports, it is celebrated in one of 660-3300 infants and can be combined with other hereditary disorders of the musculoskeletal system, such as sindakteliya, brachydactyly and Hip Dysplasia.
Etiology of polydactyly poorly understood, but is considered to be the main cause of genetic predisposition. The probability of transmission of inherited abnormalities is 50%, as a dominant trait polydactyly is characterized by a low degree of penetrance. Thus, the carrier of the gene can be born and a healthy baby.
In some versions, the pathology can occur in 5-8 week embryo development due to the uneven increase in the number of mesodermal cells. Also, sometimes it is only a symptom of a serious genetic or chromosomal abnormalities. Medicine are about 120 syndromes that may be accompanied by polydactyly, among which are:
- Syndrome Rubinstein-Tybee;
- Carpenter Syndrome;
- Syndrome Smith-Lemli-Opitz;
- Syndrome Laurence-Moon-Biedl;
- Hondroektodermalnaya dysplasia;
- Trisomy 13;
- Thoracic Dystrophy asphyxiated.
Often, the exact cause of additional fingers is not possible.
Polydactyly are classified according to the location and type of doubling. Depending on what exactly duplicated fingers, there are three kinds of anomalies:
- Preaxial (radial) - thumb;
- Central - the index, middle and ring;
- Postaksialnuyu (ulnar) - the little finger.
Additional fingers on the hands and on the feet may be formed by different methods, which depend on their qualitative characteristics and functionality. Whichever type of doubling has occurred, they may be following formation:
- Rudiments. It consists of soft tissue without bones. Keeps the skin on the leg. Non-functional;
- Forked primary finger. Formed as a result of doubling the corresponding metacarpal or metatarsal. Almost always underdeveloped and has a smaller number of phalanges;
- Complete finger. It has a normal size and shape.
If polydactyly in the site of the lesion is often observed deformation of bones and joints, which eventually is able to progress and lead to secondary changes osteoarticular apparatus.
Polydactyly diagnosis is carried out using clinical, genetic, radiographic, biomechanical and other methods of research. Clinical examination of the child is carried pediatrician, orthopedics and genetics in order to identify the functional and anatomical malformations, and also determine the type of inheritance of polydactyly. Be sure to do X-rays of the affected hand or foot, to assess the state of the articular and bone apparatus. If necessary, examination of cartilaginous structures and soft tissues, performed magnetic resonance imaging. Additional techniques such as electromyography stabilography and allow to supplement the results.
Genetic analysis is aimed at drawing up of the forecast of the probability of a given pair a child with an anatomical anomaly. Since most characteristic autosomal dominant mode of inheritance of polydactyly for developing the disease enough to mutant allele is transmitted from a parent.
If a six-fingered sign of a chromosomal or genetic abnormalities that require careful prenatal diagnosis, which includes amniocentesis and chorionic villus sampling, as well as ultrasound. When the isolated polydactyly is recommended to maintain the pregnancy, and when chromosomal disorders - interrupted.
Treatment polydactyly carried out exclusively by surgery. If the extra fingers are made up of soft tissue, they are removed in the first months after birth. In other cases, resorted to surgery, not earlier than one year. It is necessary to examine the state of the main fingers that can not be done in the newborn.
Clinical data indicate that after the normal removal of additional phalanges in 70% of cases develop repeated deformation. Therefore, during the operation the elimination of extra phalanges can be combined with major deformity correction with their fingers or a recovery operation using tissue removed. From this it depends on the length of the recovery period. Sometimes normalization features hands or feet may take several years.
Isolated polydactyly treatment lends itself best at an early age. If this is a consequence of chromosomal abnormality or genetic syndrome, the prognosis depends on the severity of the underlying disease.
Prevention polydactyly is to conduct genetic counseling during pregnancy planning, and subsequently - in the implementation of prenatal diagnosis.