The term ectrodactyly is used to refer to a rare hereditary syndrome, in which there is malformation of the fingers and toes. It is characterized by the absence of the distal phalanges or complete fingers.
It can occur in one or more fingers of the hand and even affect part of the carpus and wrist. In severe cases, and when the condition affects the foot, the fibula or all four limbs may be absent.
Case of ectrodactyly in the upper limb. By Aurélie & Sylvain Mulard - Self-photographed, CC BY-SA 3.0, commons.wikimedia.org
In the most common types of ectrodactyly, the third finger of the hand is missing, creating a deep cleft in that space. The remaining fingers are attached by soft tissues. This is known as syndactyly, and it is what ends up giving the lobster claw appearance.
The syndrome includes other deformities such as cleft lip and palate, lacrimal duct obstruction, and genito-urinary defects.
Prenatal diagnosis is made through the evaluation of the limbs of the fetus by ultrasound. If the condition is confirmed, consultation with specialists in genetic counseling is recommended for the chromosome study of the parents.
Although there is no treatment for this disease, there are conservative and surgical measures that are used to improve the quality of life of the patient.
Causes
Also known as Karsch-Neugebauer syndrome, ectrodactyly is a rare condition characterized by deformity of the hands and feet. 1 in 90,000 people suffers from this disease.
Although sporadic cases have been described, these are very rare. Ectrodactyly is described as a hereditary disease that originates from the mutation of one of the genes on chromosome 7, which is the one most frequently involved in this disease.
There are two types of ectrodactyly, type I is the most common; in this, there is malformation of the hands and / or feet without any other bodily alteration.
In contrast, type II is more serious and rare. In these patients, a cleft palate is observed, in addition to the characteristic malformations. There may also be visual and genito-urinary system problems.
Signs and symptoms
The patient with ectrodactyly has a very characteristic deformity in the hands and feet. Depending on the severity of the disease, and depending on the individual's genetic mutation, different malformations are observed.
In type I ectrodactyly, abnormalities are observed in the fingers and toes, although they can occur only in one limb, their course is unpredictable.
The typical feature in these patients is the absence of the middle finger with the union of the remaining fingers on each side.
In the site that the absent finger would occupy, a deep indentation can be seen, giving the appearance of a lobster claw. This is the same for the hands and feet.
Case of ectrodactyly in the lower limb. By Aurélie & Sylvain Mulard - Self-photographed, CC BY-SA 3.0, commons.wikimedia.org
In severe cases there may be absence of more fingers and even bones of the carpus, wrist, fibula or the four limbs.
Type II ectrodactyly occurs with other malformations in addition to those seen in this syndrome.
It is commonly associated with a cleft palate and lip, partial or complete absence of teeth, tear duct abnormalities, photophobia, and decreased visual acuity. Genito-urinary malformations such as an underdeveloped kidney, among others, can also be observed.
Diagnosis
Prenatal
In control assessments pregnancy, the specialist is able to observe a facial or members with ultrasound malformation, from 8 to week of gestation.
When the characteristic malformation of ectrodactyly is evident, the disease should be suspected even if it is not present in the family.
The definitive prenatal diagnosis is made from the genetic study of the amniotic fluid, which is obtained through a procedure called amniocentesis, which generally does not represent a danger to the mother or the fetus.
Amniocentesis. By BruceBlaus - Own work, CC BY-SA 4.0, commons.wikimedia.org
Postnatal
After birth, the malformations caused by the genetic mutation are evident, so the suspected diagnosis is made from the physical examination.
Conventional radiographs of the hands and feet are used to observe the patient's skeleton, which is sometimes underdeveloped or with fetal remnants of primitive bone.
X-ray of the hands and feet of a patient with ectrodactyly. By Internet Archive Book Images - flickr.com, No restrictions, commons.wikimedia.org
Treatment
This disease has no treatment aimed at its cure. However, measures are taken so that the patient improves their quality of life and can relate to their environment in a normal way.
Thus, there are conservative techniques and surgical techniques that help the individual with ectrodactyly to carry out their daily tasks without problems.
Conservative treatment includes the use of prostheses and special insoles that improve gait and stability.
Case of ectrodactyly. By Aurélie & Sylvain Mulard - Self-photographed, CC BY-SA 3.0, commons.wikimedia.org
In the case of hand deformity, physical therapy and rehabilitation are the most helpful elements for the patient.
For its part, surgical treatment is used to optimize finger movements, improve gait and avoid foot deformity that limits the use of footwear.
In all cases, the toes are separated with syndactyly and the cleft is closed, which helps to maintain the shape of the foot and hand.
Genetic counseling
Genetic doctors have a special counseling and advice service for patients who are carriers or have diseases that can be transmitted to their children.
In the case of ectrodactyly, it is inherited in a dominant way. That is, the children of the gene carriers have a 50% chance of suffering from the disease.
Autosomal dominant inheritance. By nih.gov, Public Domain, commons.wikimedia.org
Genetic counseling is responsible for explaining this form of transmission, as well as the chances that children have the disease.
Ectrodactyly is a condition that causes a great psychological impact for both the patient and their families, even generating rejection of the patient.
Genetic counseling seeks to prepare parents for this situation, in case the diagnosis of the disease has been confirmed in an unborn child.
Genetic counseling is an essential service in the case of inherited diseases.
References:
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- Rivas, A; Campagnaro, J; Garcia, Y; Brito, M; Morantes, J. (2014). Ectrodactyly of the foot. Report of two cases. Mexican orthopedic act. Taken from: scielo.org.mx
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- Jindal, G; Parmar, V. R; Gupta, VK (2009). Ectrodactyly / split hand feet malformation. Indian journal of human genetics. Taken from: ncbi.nlm.nih.gov