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Family Balancing & Gender Selection in Dubai

26
Sep

Family Balancing & Gender Selection in Dubai

Purpose

Given a choice and medical assistance, some Couples seek to conceive a baby with their preferred gender, either a boy or a girl on social grounds for family balancing.

Occasionally gender selection with medical assistance is recommended on medical grounds to avoid certain genetic conditions that are predominantly seen either in male or female babies.

How gender is determined in natural pregnancies

The sex ratio for the entire world estimated in 2017 is 102 males to 100 females.  

Gender is only determined by a sperm not an egg.

A healthy sperm that is carrying one Sex Chromosome called ‘Y’ plus 22 other critical chromosomes ( a total of 23 chromosomes) succeeds in fertilising a healthy egg that can only carry  Sex Chromosome ‘X’ plus 22 other critical chromosomes (a total of 23 chromosomes) , results in male embryo that can subsequently develop to be a male child.

A healthy sperm that is carrying one Sex Chromosome called ‘X’ plus 22 other critical chromosomes (a total of 23 chromosomes) succeeds in fertilising a healthy egg that can only carry Sex Chromosome ‘X’ plus 22 other critical chromosomes ( a total of 23 chromosomes) , results in female embryo that can subsequently develop to be a female child.

Presence of all 46 chromosomes (as 23 pairs) including one X from egg and one Y from sperm is mandatory for male gender embryo to develop into a healthy foetus and one X from egg and one Y from is mandatory with their complete structure is essential 

How gender can be determined before conception through Assisted Conception Techniques

Three Methods that are very reliable (close to 98-99%) for Gender identification of an embryo, from one to few cells biopsied, processed and genetically analysed, before it is transferred to women’s uterus, called Pre-implantation Genetic Tests (PGT).

This is relatively new technique and couple should be aware of:

– No guarantee of normal child being born despite genetic screening of embryos for gender,

– Costs and risks of IVF-ICSI and PGT including potential unknown risks yet to be identified.

– Risks of miscarriage

– Need for re-confirmatory gold standard tests recommended in pregnancy for chromosomal abnormalities (such as Chorion Villus Sampling, Amniocentesis) and detailed foetal anomaly ultrasound by licensed specialists. 

THREE GENETIC SCREENING TESTS FOR GENDER IDENTIFICATION

  1. Florescent in situ hybridization (FISH) accurately identifies the sex chromosome pair of XX (girl) or XY (boy) embryo and in addition can detect numerical problems of another 3 pairs of chromosomes; Chromosome Pairs 21, 18 and 13.

Merits:

Not only the gender of the embryo is accurately identified but this allows selection of embryos without any chromosomal abnormality in the specific 4 pairs of chromosomes, XX, XY, Chromosome pair 21, Chromosome pair 18, Chromosome pair 13). Consequently, there is a higher chance of a successful pregnancy, compared to those without embryo screening with FISH-PGT.

Similarly, deselection of embryos with abnormalities in any of the 4 pairs of chromosomes, example Down’s syndrome (chromosome pair 21) Edward’s syndrome (chromosome pair 18) Patau syndrome (chromosome pair 13) is expected to reduce the risk of miscarriage as most of the miscarriages are linked to chromosomal abnormalities.

In addition, it allows to couple to decide and avoid if they so wish, the risk of babies born with any of the above syndromes including those with sex chromosome abnormalities such as Turner Syndrome and Klinefelter’s syndrome associated with morbidity.

Relatively less expensive compared to aCGH and NGS

Demerits:

Incomplete genetic assessment as 19 out of 23 pairs of chromosomes are not tested for, therefore pregnancy may still not happen despite transfer of chosen gender embryos even of good grade.

  • Array Comprehensive Genetic Hybridization (aCGH)

With this comprehensive genetic screening test, the Pair of Sex chromosomes (XX or XY) along with remaining 22 pairs of chromosomes are identified for their presence or absence and any structural abnormalities.

Merits: Complete genetic assessment of 23 pairs of chromosomes, therefore embryos with various numerical errors can be accurately identified allowing clinician and couple to select and deselect accordingly which embryos to transfer and which ones not to transfer.

Over and above the chosen gender, if present, much higher chance of success rates and less risk of miscarriage is as also expected as all 23 pairs are screened and only chromosomally normal embryos of preferred gender are utilised for embryo transfer.

Demerits: Relatively expensive compared to FISH

Detection Limits

1-2% false positive or false negative results

Limitations

Embryos with no results and the need for repeat biopsy.

Because of comprehensive screening of all 23 pairs, there is significantly higher risk of not having any suitable embryo to transfer despite finding embryos with chosen gender as these preferred gender embryos may carry abnormalities of any of the remaining 22 pairs, that precludes them from usage.

Limitations:

This popular test is gradually replaced with more advanced and sensitive genetic technique called Next Generation Sequencing (NGS)

  • Next Generation Sequencing (NGS)

The Pair of Sex chromosomes (XX or XY) along with remaining 22 pairs of chromosomes are identified for their presence or absence and any structural abnormalities.

Merits: Complete genetic assessment of 23 pairs of chromosomes, therefore embryos with various numerical errors can be accurately identified allowing clinician and couple to select and deselect accordingly which embryos to transfer and which ones not to transfer.

Over and above the chosen gender, if present, much higher chance of success rates and less risk of miscarriage is as also expected as all 23 pairs are screened, and only chromosomally normal embryos of preferred gender are utilised for embryo transfer.

Demerits: Relatively expensive compared to FISH

Detection Limits

1-2% false positive or false negative results

Limitations

Embryos with no results and the need for repeat biopsy.

Methods that are less reliable and unavailable in UAE

There is a technique with limited evidence called Sperm Sorting Technique that will pool sperm sample with higher proportion of ‘Y’ chromosome containing sperm or ‘X’ containing sperm but there will always be mixture of both ‘Y’ and ‘X’ carrying sperm in the same sample therefore, false positive and false negative outcomes of Gender Identification.

Enriched mixed sample of both Y and X carrying Sperms but with higher proportion of either ‘Y’ or ‘X’ carrying sperm can then be used either for intrauterine insemination or in vitro fertilization or ICSI

Details of the procedure involved

Detailed Patient Information Sheet on IVF-ICSI, complications of IVF-ICSI and Pre-implantation Genetic Testing are available on request.