T cells disorder

Hi everyone, today we are going to explain about the "soldiers", do u remember? the T cells. 

So, in this topic we will talk about the most well know T cell disorder: DiGeorge syndrome, also known as velo-cardio-facial syndrome, Shprintzen syndrome,conotruncal anomaly face syndrome, Strong syndrome, congenital thymic aplasia, and thymic hypoplasia (For the USMLE purpose DiGeorge is fine, Dr. DiGeorge described this syndrome in 1968).

This is a congenital disorder due to a deletion in chromosome 22 (22q11.2, this is the long arm of the chromosome). The patients will present hypoplasia or aplasia of thymus and parathyroids (remember that the problem here is in the 3th and 4th pharyngeal pouches)

In this case there is increase risk for opportunistic infections (remember we don't have our "soldiers"), so patients can present with fungi and viruses early in life.

To remember the features of the syndrome we have the nmenomic: CATCH - 22, where 22 is to remember the chromosome number, so here we go: C for cardiac abnormalities (Fallot), A stands for abnormal facies, T stands for thymic aplasia (hypoplasia), C stands for cleft palate and finally H stands for hypocalcemia and hypothyroidism, 

C: cardiac

A: abnormal facies 

T: thymic aplasia

C: cleft palate

H: hypocalcemia, hypothyroidism

Now in some cases the hypocalcemia might be helpful in the diagnosis, because sometimes the only presentation in a neonate are seizures (due to hypocalcemia). Other Lab findings include: decrease lymphocytes (with decrease CD3+ which is the marker for the T cells), and a normal level of immunoglobulins (remember that B cells are normal here)

Also a important thing to remember (and always asked) is the association of DiGeorge and the increase risk (up to 20 to 30 times) to develop schizophrenia. 

For the treatment we have to treat based on each case, if the patient have cardiac abnormalities, he might require cardiac surgery, if he is having infections he might need antibiotics or antifungals, for the hypocalcemia or hypothyroidism the patient may need vitamin D and calcium supplement, and in rares cases (of fully thymic aplasia) the patient may require thymic transplant.

So in summary, remember the chromosome number (22), the presentation (CATCH), the lab findings (hypocalcemia and hypothyroidism) and the association with schizophrenia.

The next topic will be about phagocytic system disorders, 

Hope you enjoy the reading,

See you on the next post

Carlos Albrecht