This letter will summarize the testing performed on blood obtained from [PROBAND] to determine the cause of [HIS/HER] hearing loss.
We met with [CLIENT] to discuss these results in [CLINIC] on [DATE].
[PROBAND'S] blood was obtained to determine if [HIS/HER] hearing loss was due to a change in a gene called GJB2 (for gap junction protein beta 2) that is associated with childhood hearing loss.
This is also called Connexin 26 testing.
Approximately 60% of childhood hearing loss is genetic; that is, caused by an alteration of genetic information.
As with most children with a genetic hearing loss, [PROBAND] has no unusual features and has what is called "isolated" or "non-syndromic" hearing loss.
Although changes in many different genes can cause deafness, about 50% of children with severe to profound recessively inherited non-syndromic genetic hearing loss have a change in one particular gene called GJB2.
The most common change in this gene causing deafness is called 35delG and involves the loss (deletion) of a small piece of genetic material within the gene.
The change found in [PROBAND'S] GJB2 gene was a rarer change and is called [CHANGE].
This change is known to result in a shortened or truncated protein.
The protein, called Connexin 26, is important in maintaining the chemical equilibrium of the inner ear.
We briefly discussed autosomal recessive inheritance.
It is believed that we all carry some altered genes that may cause health problems in ourselves or our children.
The chance of being a carrier of a particular altered gene can be estimated by our family history and ethnic background.
When there is no family history of childhood deafness, an individual in the general Caucasian population has about a 2 to 3% (2 to 3 out of 100) chance of being a carrier of an altered GJB2 gene.
Hearing loss caused by the [CHANGE] mutation is inherited in an autosomal recessive pattern.
To understand this type of inheritance, it is important to know that genes occur in pairs.
One member of each pair is inherited from each of our parents.
The members of the gene pair are called "alleles".
One allele for the GJB2 gene is inherited from our mother while the other allele is inherited from our father.
When both parents have one altered copy and one unaltered copy of the GJB2 allele, they are not usually deaf.
In fact, most individuals do not know they carry an altered gene until they have a deaf child.
Children who inherit two altered alleles (one from each parent) will have hearing loss.
The unaffected parents are called "carriers".
A couple in which both are carriers have a one in four (25%) chance that a child they conceive will inherit both altered alleles and will have hearing loss.
This also means that they have a three in four (75%) chance that a child will inherit one unaltered allele from at least one parent and not have hearing loss.
These chances are the same for each pregnancy they have together.
This is called autosomal recessive inheritance
Many genetic conditions, such as cystic fibrosis and sickle cell anemia, are inherited in this way.
It is estimated that everyone has a number of gene changes that can cause problems in our children if our partner is also a carrier.
It is important to remember that we have no control over which genes our children inherit.