SHHHhHere are some Frequently Asked Questions about Prenatal Referrals to Medical Genetics: 

Should I refer my pregnant patient who has a family history of cystic fibrosis (CF) to Medical Genetics?

 

If your patient would like to know their chance of having a child affected with CF, and/or would choose prenatal diagnosis if it was indicated, then the pregnant person and their partner should be offered the option of carrier testing for CF. This can be arranged by using the genetic test requisition available online at: http://www.genebc.ca/

It's important to note that the standard CF carrier screen in BC is not able to exclude carrier status with 100% certainty. Knowledge of the specific CFTR gene variants in the family is useful in the interpretation of a negative genetic test result. Ideally, the genetic test report of the affected family member should be submitted along with the test requisition.

If both the pregnant patient and the partner are carriers for CF, each of their pregnancies will have a 25% chance of being affected, and a referral to Medical Genetics is indicated. 

My pregnant patient (or the father of the pregnancy) has a relative who is affected with a genetic condition. Should I refer them to Medical Genetics?

 

First, it would be important to obtain medical records documenting the diagnosis in the affected person. Ideally this is both a clinical consultation letter, and if lab testing was done the lab reports. This Release of Information consent form may be helpful: http://www.bcchildrens.ca/your-visit-site/Documents/Release%20of%20Information%20Form.pdf

Next, it would be useful to understand your patient's feelings about having a child affected with the condition in the family. If they have a good understanding of the natural history of the condition and they are accepting of the possibility of having an affected child, they may not need genetic assessment and counselling during the pregnancy. If your patient would like information about the chance of having an affected child and/or would choose prenatal diagnosis if it was an option, then you could submit a referral to Medical Genetics along with the documentation of the genetic condition in the affected family member, for review by our triage team. 

My pregnant patient has alpha thalassemia trait (carrier for alpha thalassemia) and her partner has beta thalassemia trait (carrier for beta thalassemia). Should I refer them to Medical Genetics?

 

Alpha thalassemia and beta thalassemia are autosomal recessive conditions that are caused by two different genes. If one partner is a carrier for alpha thalassemia (trait) and the other partner is not, their pregnancy is not at significant risk to be affected with alpha thalassemia major. Similarly, if one partner is a carrier of beta thalassemia (trait) and the other partner is not, their pregnancy is not at significant risk to be affected with beta thalassemia major. However, beta thalassemia trait can sometimes mask alpha thalassemia trait. Molecular analysis of the alpha globin genes may be needed in the person with beta thalassemia trait to further assess for carrier status for alpha thalassemia. Sometimes, alpha thalassemia trait is referred to as thalassemia minor or a single or double alpha globin gene deletion. Individuals of certain ethnic backgrounds are more likely to be carriers of a hemoglobinopathy such as thalassemia. More information about who should be screened can be found online at: https://geneticseducation.ca/wp-content/uploads/2014/06/Ethnicity-based-screening-POC-tool-FINAL-June-2014.pdf

Carrier testing can be done for both partners by requesting a "hemoglobinopathy investigation" which consists of an analysis of the different types of hemoglobin as well as the red cell indices. More information about the recommendations of the Society of Obstetricians and Gynecologists of Canada about carrier screening for this group of disorders can be found online at: https://www.jogc.com/article/S1701-2163(16)32975-9/pdf

If both partners are carriers for the same type of thalassemia, a referral to Medical Genetics is warranted. 

My pregnant patient (or the father of the pregnancy, or their child) was born with a cardiac defect or other congenital anomaly. Should I refer to Medical Genetics?

 

The majority of congenital anomalies are isolated i.e. the patient has normal intellect, no dysmorphic features, and no other congenital malformations or chronic illness. Most isolated congenital anomalies are multifactorial in etiology, meaning that they are caused by a combination of genetic and environmental factors. These typically occur sporadically, and the chance for the affected person's child to be similarly affected is slightly increased over the background population incidence. However, if there are multiple members of the same family affected, there may be more of a genetic component and a higher chance for recurrence.

If there is a family history of a first degree relative to the fetus with a congenital heart defect, your patient may be eligible to have a screening fetal echocardiogram (or a detailed fetal ultrasound with extended heart views at a tertiary center) in her pregnancy. This can be booked directly with the ultrasound department at BC Women's Hospital or Jim Pattison Maternal Fetal Medicine.

A Medical Genetics consult is only indicated if there is a conotruncal cardiac malformation such as: tetralogy of Fallot, truncus arteriosus, interrupted aortic arch-B, or a conotruncal VSD. These specific conditions can be associated with higher recurrence chances in a family. A referral to Medical Genetics for assessment of the individual with the cardiac malformation may be warranted to determine if genetic testing is indicated. This can help inform the chance for recurrence in the pregnancy.

My pregnant patient and the partner (the father of the pregnancy) are first cousins. Should I refer them to Medical Genetics?

 

If there is a family history of intellectual disability, congenital abnormalities, stillbirth, recurrent pregnancy losses, or a genetic condition and the couple is interested in learning more information about their chance to have a similarly affected child and/or would consider prenatal diagnosis if offered, then a referral can be submitted for review by our triage team. Please include any relevant family medical records and/or signed release of information forms http://www.bcchildrens.ca/your-visit site/Documents/Release%20of%20Information%20Form.pdf.

We do not have the capacity to accept referrals for first cousin consanguinity in the absence of additional risk factors. You may wish to inform your patient that the chance for a newborn in the general population to have a congenital anomaly or disabling condition is estimated to be 3-5%. The chance for the same in the offspring of consanguineous couples is roughly 6-10%. The patient should be offered the option of routine prenatal screening and a detailed fetal ultrasound exam. If any fetal malformation is identified, a referral to the Fetal Diagnosis Service may be warranted. You may review the referral criteria online at: http://www.bcwomens.ca/health-professionals/refer-a-patient/fetal-diagnosis-service

My pregnant patient had a detailed fetal ultrasound exam that showed an echogenic intracardiac focus (or other soft marker for aneuploidy such as: choroid plexus cysts, increased nuchal thickness, aberrant right subclavian artery, pyelectasis, echogenic bowel, or short femur). Should I refer to Medical Genetics?

 

Using your patient's age or screening results, you can calculate the chance of the fetus being affected with Down syndrome using the trisomy 21 calculator on the Perinatal Services BC website at: https://www.psbchealthhub.ca/clinical-guidance/calculators/39

If the algorithm indicates that the patient is eligible for amniocentesis or for provincially funded cell free DNA screening (NIPT), you can provide information about each of these options to the patient and arrange their test of choice. The code for provincially funded NIPT can be obtained by phoning the Medical Genetics clinic in Vancouver (604-875-2157) or Victoria (250-727-4461).

Choroid plexus cysts are associated with a slightly increased chance for the fetus to be affected with trisomy 18.  In the absence of fetal growth restriction or structural fetal malformations, the chance that the fetus is affected with trisomy 18 is very low and no further testing is indicated. 

My pregnant patient had a previous pregnancy affected with trisomy 21 (or trisomy 18 or trisomy 13). Should I refer to Medical Genetics in the current pregnancy?

 

The vast majority of cases of trisomy are sporadic and are associated with a low chance for recurrence in subsequent pregnancies. Your patient is eligible for invasive prenatal diagnosis for rapid aneuploidy detection via chorionic villus sampling or amniocentesis. If she prefers a noninvasive test, she could opt instead for provincially funded cell free prenatal DNA screening (NIPT). A code for this could be obtained by phoning the Prenatal Biochemistry Laboratory at BC Children's Hospital at 604-875-2331. A referral to Medical Genetics is not indicated if there is no evidence of an inherited chromosome rearrangement in the family.

In a small minority of patients, their previous pregnancy with aneuploidy is due to a heritable chromosome rearrangement. If your patient or their partner carries a balanced chromosome translocation or other chromosome rearrangement, a referral to Medical Genetics is warranted for discussion of the risks and prenatal testing options. It would be important to submit the report documenting the chromosome rearrangement along with the referral. 

Prenatal Referral Form (PDF) (Fillable)