Hong Kong Preimplantation Genetic Testing (PGT) Technology and Process Explained

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Author: Reproductive Medicine Knowledge Editor ｜ Reviewer: Consultant, Hong Kong Reproductive Medicine Center ｜ Updated: April 2025

A 34-year-old woman consulted because her husband is a carrier of a balanced chromosomal translocation. She had experienced two previous miscarriages and has an AMH level of 1.9 ng/mL. She hopes to understand whether she can screen for chromosomally normal embryos for transfer through preimplantation genetic testing in Hong Kong. This is a typical PGT-SR (chromosomal structural rearrangement) case in a reproductive genetics clinic. Her core needs are to reduce the risk of another miscarriage and to have a healthy child. Addressing this requires a systematic assessment of her ovarian reserve, the breakpoints of the translocated chromosomes, and the PGT technical pathways of different fertility centers in Hong Kong.

1. What is Preimplantation Genetic Diagnosis? (PGD / PGT)

Preimplantation genetic diagnosis, often referred to as "third-generation IVF" in the field of assisted reproduction, is formally known academically as PGT (Preimplantation Genetic Testing). It is based on in vitro fertilization (IVF) and involves performing a trophectoderm biopsy on a blastocyst cultured to day 5 or 6, removing approximately 3-5 cells for genetic analysis. This allows for the selection of embryos that do not carry specific disease-causing genes or have normal chromosomes for transfer.

Based on the purpose of the testing, PGT is divided into the following three categories:

• PGT-A (Aneuploidy Screening): Detects whether there is an increase or decrease in the number of chromosomes in the embryo (e.g., Trisomy 21, Trisomy 18). Suitable for individuals of advanced maternal age, those with recurrent implantation failure, or recurrent miscarriage.
• PGT-M (Monogenic Disease Diagnosis): Targets known pathogenic loci for single-gene disorders (e.g., thalassemia, spinal muscular atrophy, cystic fibrosis). Requires the construction of family linkage analysis probes first.
• PGT-SR (Structural Rearrangement): Specifically for carriers of structural abnormalities such as balanced translocations, Robertsonian translocations, and inversions, to select embryos with normal chromosomal structure.

2. Why Choose Hong Kong for PGT? — Regional Differences and Technical Features

Assisted reproductive technology in Hong Kong is regulated by the Hong Kong Council on Human Reproductive Technology (HKHRTA). Its regulatory framework is aligned with international standards, with strict control over PGT indications, and it explicitly prohibits sex selection for non-medical reasons and embryo gene editing. Compared to Mainland China, laboratory accreditation standards for PGT in Hong Kong place greater emphasis on international third-party quality control (e.g., UKAS accreditation). Many centers use whole-genome sequencing technology for genetic analysis, allowing simultaneous screening for chromosomal aneuploidies and known pathogenic loci.

Compared to North America or Europe, Hong Kong's advantages include no language barriers, geographical proximity, short flight times, and some centers accept embryo transport from carrier couples. However, it is important to note that the total cost for PGT in Hong Kong typically ranges from HKD 150,000 to 250,000 (including genetic probe construction, biopsy, and analysis), which is higher than in first-tier cities in Mainland China but lower than in the United States.

Comparison of PGT Features at Major Hong Kong Fertility Centers

Note: The technology platforms and fee structures of each center are subject to dynamic updates. Please refer to the plan provided during your consultation.

3. What is the Actual Process? (Step-by-Step Breakdown)

The complete PGT process in Hong Kong is tightly coordinated, requiring precise time management at each stage. The following is a standardized pathway:

1. Genetic Counseling and Preliminary Testing (Takes 1-2 months): Both partners undergo peripheral blood karyotype analysis and gene sequencing verification. For single-gene disorders, blood samples from the proband (affected child or both parents) are needed to construct detection probes. This step is crucial for determining the feasibility of PGT.
2. Registration and Legal Document Signing: According to HKHRTA regulations, couples must sign informed consent forms specifying the scope of PGT testing, embryo disposition plans, and data privacy terms.
3. Ovarian Stimulation and Egg Retrieval: An individualized ovarian stimulation protocol (e.g., antagonist protocol or follicular phase long protocol) is used, aiming to retrieve 8-15 mature oocytes.
4. In Vitro Fertilization and Blastocyst Culture: After fertilization via ICSI (Intracytoplasmic Sperm Injection), embryos are cultured to the blastocyst stage on day 5-6. Blastocyst-stage biopsy causes less disturbance to the embryo and provides more cells for analysis.
5. Embryo Biopsy and Cryopreservation: A hole is made in the zona pellucida, and 3-5 trophectoderm cells are aspirated. The biopsied blastocyst is immediately cryopreserved by vitrification while awaiting test results.
6. Genetic Analysis (Takes 2-4 weeks): Whole genome amplification and sequencing of the biopsied cells are performed using NGS or aCGH technology. The report will show the embryo's chromosomal copy number variations and information on target gene loci.
7. Thawed Embryo Transfer and Luteal Support: A chromosomally normal/unaffected embryo is selected for thawed embryo transfer. A blood test is done 10-12 days after transfer to confirm pregnancy.
8. Prenatal Diagnosis Confirmation: Amniocentesis is recommended at 16-20 weeks of pregnancy for final confirmation of the fetal chromosome or gene status.

4. Easily Overlooked Details and Risks

In clinical consultations, the following 3 issues are often overlooked by patients but are critically important:

• Management of Mosaic Embryos: Some embryos contain both normal and abnormal cell lines, and the genetic report may indicate "low-level mosaicism." Whether such embryos can be transferred requires a comprehensive assessment by a genetic counselor, considering the specific mosaic ratio, the chromosomes involved, and the patient's reproductive history.
• Limitations of Testing Platforms: PGT-A cannot screen for microdeletions/microduplications (requires specific probes), and PGT-M cannot cover diseases with unknown pathogenic loci. It is essential during genetic counseling to clearly communicate the "scope of testing" and the "residual risk."
• Impact of Poor Ovarian Response on PGT: If the number of eggs retrieved is low, the number of blastocysts formed will be limited, and there may be no embryos that pass the genetic screening. For women with diminished ovarian reserve (AMH < 0.8 ng/mL), the need for accumulating embryos over multiple cycles should be discussed in advance.

5. Detailed Explanation of Cost Factors

The cost structure for PGT in Hong Kong is relatively transparent and mainly includes the following components:

The main factors influencing the total cost are: whether new genetic probes need to be constructed (for single-gene disorder families), the number of embryos biopsied, and whether repeated cycles are necessary. Most Hong Kong fertility centers offer package deals, but it is important to carefully check the number of tests and the scope of items included in the package.

6. How to Choose the Right PGT Center for You?

When evaluating different fertility centers, it is recommended to assess them based on the following 4 dimensions:

• International Accreditations Held by the Lab: Laboratories accredited by CAP (College of American Pathologists) or UKAS (United Kingdom Accreditation Service) typically have more robust quality control systems.
• Genetic Counseling Team Configuration: Does the center have full-time genetic counselors? Can they provide report interpretation in both Chinese and English? For complex translocations or rare genetic diseases, the experience of the genetic counselor directly determines the accuracy of the testing plan.
• Embryologist Experience: The consistency of biopsy procedures is directly related to the embryologist's seniority. Inquire about the center's annual biopsy volume and blastocyst formation rate.
• Collaboration Network with Hospitals in Mainland China: Some Hong Kong centers have referral partnerships with tertiary hospitals in Mainland China, allowing for mutual recognition of preliminary tests and reducing the hassle of repeat testing.

7. Frequently Asked Questions (Q&A)

Q1: Can PGT screen for all genetic diseases?

A: No. PGT currently primarily targets chromosomal number abnormalities, structural abnormalities (translocations, inversions), and single-gene disorders with known pathogenic loci. Polygenic genetic diseases (such as diabetes, hypertension, schizophrenia, etc.) and birth defects caused by environmental factors are not within the screening scope of PGT.

Q2: Are there restrictions on embryo sex selection for PGT in Hong Kong?

A: Yes, there are strict restrictions. According to the regulations of the Hong Kong Council on Human Reproductive Technology, PGT for sex selection solely for non-medical reasons is strictly prohibited. If it is to avoid an X-linked genetic disease (such as hemophilia, Duchenne muscular dystrophy), it is considered a legitimate medical indication.

Q3: What if there are no normal embryos available for transfer after PGT?

A: This is the most important risk to accept in advance for a PGT cycle. For individuals with normal ovarian reserve, the probability of having no transferable embryos is approximately 10-15% (varying by age and type of genetic abnormality). In such cases, the doctor will recommend genetic counseling to analyze whether carrier embryo transfer is possible (requires thorough risk assessment), or to consider egg donation/embryo donation.

Q4: What is "mitochondrial replacement" or "three-parent IVF"? Is it available in Hong Kong?

A: Currently, Hong Kong law prohibits reproductive cloning and gene editing involving human embryos. There is no clear legislation yet on mitochondrial replacement therapy (MRT), and it is extremely rare in clinical practice and not routinely performed. Families at risk for mitochondrial diseases should first seek genetic counseling to evaluate other available options.