Polydactylia

The polydactylia is an inborn pathology of development of fingers which is expressed in increase in their quantity. It is more often observed on hands, but can affect also toes, or at the same time upper and lower extremities.

As a rule, this anatomic defect is inherited as a dominant character at a polydactylia from one of parents. It is not life-threatening, but can become the reason of a psychological injury, break functions of extremities, and also slow down physical development and limit choice of profession in the future.

Statistically, the polydactylia meets identical frequency at boys and girls. According to various data, it is noted at one of 660-3300 babies and can be combined with other inherited disorders of a musculoskeletal system, such as syndactylia, brachydactyly and dysplasia of joints.

Polydactylia reasons

The etiology of development of a polydactylia is insufficiently studied, but genetic predisposition is considered the main reason. The probability of transfer of anomaly by inheritance makes 50% as the dominant character of a polydactylia is characterized by low degree of penetrance. Thus, at the carrier of a gene also the healthy child can be born.

According to some versions, pathology can arise at an embryo on 5-8 week of development because of uneven increase in quantity of mesodermal cells. Besides, sometimes it is only one of symptoms of serious gene or chromosomal violations. The medicine knows about 120 syndromes which can be followed by a polydactylia, among which it is possible to call:

• Rubenstein-Taybi syndrome;
• Carpenter's syndrome;
• Syndrome Smith-Lemli-Opitz;
• Syndrome of Laurens-Mun-Biyedl;
• Hondroektodermalny dysplasia;
• Trisomy 13;
• Thoracic dystrophy with asphyxia.

Often it is not possible to establish an exact origin of additional fingers.

Classification of a polydactylia

The polydactylia is classified by localization and type of doubling. Depending on what fingers are duplicated, distinguish three types of anomaly:

• Preaksialny (radial) – a thumb;
• Central – index, average and anonymous;
• Post-axial (ulnarny) – a little finger.

Additional fingers as on hands, and standing, can form in the different ways on which their qualitative characteristics and functionality depend. Depending on what type doubling took place, they can represent the following educations:

• Rudiment. Consists of soft tissues, without bones. Keeps on a skin leg. It is nonfunctional;
• The doubled main finger. It is formed as a result of doubling of the corresponding metacarpal or plusnevy bone. It is almost always underdeveloped and has smaller number of phalanxes;
• Full-fledged finger. Has the normal sizes and the form.

At a polydactylia in the place of defeat deformation of bones and joints which is capable to progress and lead to secondary changes of the bone and joint device over time is quite often observed.

Diagnosis of pathology

Diagnosis of a polydactylia is carried out by means of clinical, genetic, radiological, biomechanical and other techniques of a research. Clinical examination of the child is performed by the pediatrician, the orthopedist and the geneticist to reveal functional and anatomic disturbances of development, and also to establish a polydactylia mode of inheritance. Surely the X-ray analysis of the struck brush or foot becomes to estimate a condition joint and the ossa. In need of survey of cartilaginous structures and soft tissues, the magnetic and resonant tomography is carried out. Additional methods, such as a stabilografiya and an electromyography, allow to add the received results.

The genetic analysis is directed to drawing up the forecast of probability of the birth at this couple of the child with anatomic anomaly. As the autosomal and dominant mode of inheritance of a polydactylia is most characteristic, for a course of a disease it is enough that the mutant allele was transferred from one of parents.

If the shestipalost represents a symptom of a chromosomal or genetic deviation, careful prenatal diagnosis which includes amniocentesis and a biopsy of chorion, and also ultrasonography is necessary. At the isolated polydactylia pregnancy is recommended to keep, and at chromosomal disturbances – to interrupt.

Treatment of a polydactylia

Treatment of a polydactylia is carried out by exclusively surgical way. If additional fingers consist of soft tissues, then delete them in the first months after the birth. In other cases resort to an operative measure not earlier, than in a year. It is necessary to study a condition of the main fingers that cannot be made at the newborn.

Clinical data demonstrate that after usual removal of additional phalanxes repeated deformation develops in 70% of cases. Therefore during operation elimination of additional phalanxes can be combined with correction of deformation of the main fingers or with their recovery by means of remote fabrics. Duration of the recovery period also depends on it. Sometimes for normalization of functions of brushes or feet several years can be required.

The isolated polydactylia will respond to treatment best of all at early age. If this pathology is a consequence of a chromosomal or gene syndrome, then the forecast depends on weight of a basic disease.

Prevention of a polydactylia consists in carrying out genetic consultations during pregnancy planning, and afterwards – in implementation of prenatal diagnosis.