Beta ketothiolase deficiency

Couples who are at high risk for having a child with beta ketothiolase deficiency have several options that may be available either before a pregnancy or during a pregnancy. The optimal time to determine genetic risk, clarify carrier status of parents, and discuss the availability of prenatal testing is before pregnancy. Genetic counseling (which includes a discussion of potential risks to offspring as well as reproductive options) is recommended for individuals who are affected, are carriers, or are at risk of being carriers for genetic disorders.

Finding out the genetic status of the fetus during a pregnancy for pregnancies at high risk (i.e. those at 25% risk based on family history) is possible either by analyzing T2 activity (the defective enzyme in the disorder) or by detecting mutations in fetal DNA.^[1] These tests can be performed following either chorionic villus sampling (CVS) between approximately 10 and 12 weeks gestation, or amniocentesis usually between 15 and 18 weeks gestation. For couples seeking DNA analysis to identify whether the fetus has inherited specific disease-causing mutations, the mutations in an affected family member or in the carrier parents must be known before prenatal testing can be performed.

As an alternative to prenatal diagnosis during the pregnancy, preimplantation genetic diagnosis (PGD) may be available months before a pregnancy begins if the disease-causing mutations have been identified. Preimplantation diagnosis is done following in vitro fertilization (IVF) to diagnose a genetic disease in an embryo before it is introduced into the uterus. When doing PGD, laboratories can test a single cell from an embryo that is just days old. Besides testing for the specific disorder in question, PGD can also provide information about whether the embryo is male or female and whether it is carrying chromosomal abnormalities or rearrangements.^[2]

GeneTests lists the names of laboratories that are performing testing for beta ketothiolase deficiency. Please note that most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional. To view the contact information for the clinical laboratories conducting testing (including prenatal diagnosis), click here. For a list of laboratories that offer PGD, click here.

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.