What is ABCD Syndrome?

May 16 23:47 2019 Print This Article

The ABCD syndrome denotes albinism, black lock, cell migration of the gut which involves neurocytes, and the deafness which is sensorinueral. The mutation in the gene is responsible for it. The gene which is involved is known as EDNRB which stands for endothelin B receptor gene. It is considered to be a type of waardenburg syndrome. It is also known as shah waardenburg syndrome. It is considered to be of homozygous mutation and was misdiagnosed early.

What is the history and cause of ABCD syndrome?

The ophthalmologist of Dutch known as P J Waardenburg gave an idea about the Waardenburg syndrome when he examined the deaf patients. He takes into account all the symptoms patient had and he defined the displacement of medial canthi along with the dystopia of lacrimal punctum and blepharophimosis. It includes the people with broad and flat nose which forms the folds in skin and covers the corners of eye. The people with a unique nasal root are broad and have a wide area within the eyes which lead to flat and wider face. It also shows the hypertrichosis of eyebrows which lead to more growth of hair in the eyebrow region. It rather appears as a unibrow.

Another symptom was the presence of white forelock which denotes the depigmented parts of hair. It also included the heterochromia iridis which means an individual with two different color eyes. The same eye also has a different color. There is another symptom of deaf mutism which denotes to the deaf and mute people.

There are wide varieties of symptoms in the syndrome and they occur in the different combinations. The different forms of waardenburg syndrome have different symptoms. They can be further of type 1, type 2, type 3 and type 4. In the year 1995 a case study was done in the Kurdish family. The molecular analysis of DNA strands was done by few scientists of the patients suffering from this syndrome. It helped to know the sequence of mutation in the EDNRB gene. This is the common protein coding gene. A transition was seen from homozygous C to T. It occurred at the amino acid level at a premature stop codon. They go back and cause mutations in the EDNRB gene. There were mutations in other genes also like SOX10.

The ABCD syndrome is a type of shah waardenburg syndrome. The genetic tests on the patient of DNA also help to diagnose the syndrome. A scientist known as Whitkop looked at the patients with white hair, skin without the pigmentation, black locks and diagnosed them as BADS which refer to the black lock albinism deafness. It is basically an autoimmune disorder and is not linked to the genetic causes. The children of Kurdish parents were examined and suggested an autosomal recessive inheritance. It leads to the cell migration of neurocytes in gut and redefined the syndrome. There was a non sense mutation in the EDNRB gene and was of homozygous nature. It is a part of shah waardenburg syndrome. The main cause of this syndrome is gene mutation. It is of homozygous type and researchers have established them in the last two decades. The new DNA testing methods have changed our view on this syndrome. The homozygous mutation refers to the same mutation on the maternal and paternal genes.

The scanning of Kurdish family revealed this fact. They were scanned for the different genes by the help of a test involving denaturing gradient gel electrophoresis. It relies on the electric current and the difference in melting point of DNA and RNA. They are based on their molecular weight and difference in the mobility. It can be used to determine the different sequences. It also detects the individual alleles and there are different nucleotides in DNA. They are coded for different proteins which forms different base pairs. They include the adenine, thymine, guanine and cytosine. There is a combination of adenine with thymine and cytosine with guanine. They are present on the double strands of DNA. There was an irregular pattern of DGGE of EDNRB gene.

The transition of homozygous C to T leads to mutation which occurs at the amino acid level. It stops the gene translation. The endotherlin receptor B forms a type 4 waarndenburg syndrome. Some authors suggest that ABCD syndrome is not a separate syndrome and is a part of waarndenburg syndrome. The gene involved in both the syndrome is same and now the scientists can work to fix this gene.

What is the prognosis and treatment of ABCD syndrome?

There is no specific treatment for this syndrome. The treatment is mainly symptomatic.

The person suffering from the hearing loss must be given hearing aids and the person with the complications must be treated by the colostomy.

With the advances in the gene therapy the chances of the syndrome to be cured are more. If its complication is treated the patient lives a healthy life. If it is not diagnosed early it may lead to the death in the infancy. The loss of hearing can occur with the time and is regressive in the nature. The colostomy can cause the digestive problems and may lead to the reattachment. It is mainly treated by the use of laxatives.

The surgery or hearing aids are very useful in the treatment of deaf patients.