Researchers at UNC School of Medicine have discovered a potential environmental cause of autism - prescription drugs that interfere with a critical process in DNA called topoisomerases.  Ordinarily, DNA is wound tightly in packages to ensure efficient storage and must be unwound during cell division and gene expression.  Topoisomerases make the unwinding possible that is necessary during these two crucial processes. 

Professors Mark Zylka and Benjamin Philpot made the discovery while studying a drug that’s effective against cancer and discovered that this cancer drug impacted topoisomerases.  Tompoisonmerases regulate really long genes and the genes identified as being associated with autism are really long.  This led the professors to the insight that inhibiting topoisomerases might increase the risk of autism.  In addition, most of the affected genes related to brain development in utero as well as early childhood meaning exposure to certain pharmaceuticals during those critical time periods could lead to lifelong effects such as autism even after the exposure ended.

The researchers were studying a chemo drug called topotecan but point out that other drugs such as antibiotics and antifungals also inhibit topoisomerase enzymes and this could lead to autism.  The antibiotics that inhibit antibiotics are known Quinolone antibiotics.  They go by the following

Flumequine                                     Nalidixic acid                         Enoxacin

Oxolinic acid                                   Piromidic acid                        Lomefloxacin

Pipemidic acid                                 Rosoxacin                               Nadifloxacin

Ciprofloxacin                                   Ofloxacin                               Pefloxacin

Norfloxacin                                     Balofloxacin                           Gatifloxacin

Rufloxacin                                       Grepafloxacin                         Levofloxacin

Moxifloxacin                                   Pazufloxacin                           Sparfloxacin

Temafloxacin                                   Tosufloxacin                           Clinafloxacin

Gemifloxacin                                   Sitafloxacin                            Trovafloxacin

Prulifloxacin

Antifungals such as fluconazole have also been shown to inhibit topoisomerase.