Prenatal Diagnosis of Organic Acidemias at a Tertiary Center

The aim of this study was to share our experience in the prenatal diagnosis (PND) of organic acidemias (OAs) in our clinic. This study consisted of 10 cases in whom an invasive prenatal diagnostic test (IPNDT) was performed by a single physician for the PND of OAs. Median maternal age, parity, gestational week of IPNDT, prenatal test indications, OA types, method of IPNDT, IPNDT results and gestational outcomes were evaluated. Targeted mutation analysis was performed in fetal DNA for the specific mutations by using polymerase chain reaction (PCR) and direct Sanger sequencing. The diagnosis was confirmed by genetic targeted mutation analysis after birth. Median maternal age, parity and gestational week of IPNDT values were 30 (range 21-35), one (range 0-4) and 11.5 (range 11-17), respectively. Indications for IPNDT were mother being a carrier of the disease for one case (10.0%) and at least one child with OA in the family for nine cases (90.0%). Organic acidemia types investigated were maple syrup urine disease (MSUD), methylmalonic acidemia (MMA) and isovaleric acidemia (IVA) in five (50.0%), three (30.0%) and two (20.0%) patients, respectively. Chorion villus sampling (CVS) was done in seven (70.0%) patients and amniocentesis was performed in three (30.0%) patients. Eight fetuses (80.0%) were found to be healthy and two fetuses (20.0%) were found to be affected (one case with IVA and one case with MMA). The two pregnancies (20.0%) with affected fetuses were terminated. Prenatal diagnosis of OAs is critical. Appropriate prenatal counseling should be given to families with known risk factors.