Tangier Disease

[EMTfreak]

Hi there,
I am a mom of a 2 y/o girl who just had some genetic testing done due to developmental issues and a hx of Autism in the family (brother).  They found that she is a carrier of Tangier Disease. In the report, it says that the 'significance' is unknown and that it 'unlikely' to cause problems but that further genetic screening is necessary.  The neurologist wouldn't even 'touch' the subject with a 10 foot pole!  He just said he STRONGLY suggests we get this blood work done and that we see the head of genetics for genetic counseling. The hospital is offering genetic screening for my husband and I at no cost now (we go Thursday for the blood draw) and we'll see a geneticist first week of December.  I am interested in the results as we have a lot of health issues on my mom's side of that family that follow the path of Tangier complications.
Can you tell me what the implications of this are?  From what I've read - there are conflicting opinions of significance to carriers -  I've read opinions for both sides - that it doesn't affect carriers at all and then also - from other sources, that it does affect them, but to varying degrees.
How common is it to be a carrier?  I've read that there are only 50 cases world wide.....but what about carrier status?  Is it hard to determine because they don't have symptoms?
She's only two - but does have big tonsils - although I don't believe they are orange.  She has Common Variable Immune Deficiency and if on SCIG therapy on a weekly basis to help her with that - so I am hoping that she won't have another medical issue to contend with as life for her to date hasn't been easy. I just want to know what we're facing for her - if we need to be cautious with her....
Thank you,
I appreciate your input - December is a long way to wait to get some basic answers!
Stef

[EMTfreak]

Thank you!
I appreciate your response.  I believe that they said it was a deletion in chromosone 9.
This response has given me a better idea of what to expect when we talk to genetics in December.  My husband and I had our blood drawn for the genetic testing yesterday - so now we wait......

Thanks so much again!
Stefani

[Lisa Kessler, MS, CGC]

It sounds like there is lot going on with your family.  I hope that this helps answer some of your questions before you have your genetics appointment.  

As you may have read, Tangier disease is a rare inherited disorder characterized by a severe reduction in the amount of high-density lipoprotein (HDL), often referred to as "good cholesterol," in the blood.   The gene associated with this condition is called ABCA1.  Some literature describes the inheritance of this condition as autosomal recessive, in which two altered genes cause the condition.   Most often, the parents of an individual with autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.  If someone is a carrier, then there is a 50% chance for each child to also be a carrier.  Other reports describe the inheritance as codominant.  In codominant inheritance, two different forms (alleles) of a gene can be expressed.   Both forms of the gene determine the characteristics of the genetic condition.  In people who have one gene mutation for Tangier disease often have HDL-C (High Density Lipoprotein Cholesterol) levels that are about one-half those of people without any gene mutations for Tangier Disease.  

People with Tangier disease can also have increased amounts of fat in the blood, have problems with nerve function, and can have early cardiovascular disease.  You had mentioned your daughter’s tonsils.  Tonsils are often extremely enlarged and frequently appear orange or yellow.   I am not aware of a number for carrier frequency for Tangier Disease.  However, there are common gene changes in the ABCA1 gene that affect HDL-C and affect the risk of atherosclerosis.  When you meet with genetics, you will be able to discuss the specific gene change that was identified in your daughter and discuss her medical history and family history.  I wish you the best with the appointment.