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Chromosomal diseases diagnostics

World Health Organization (WHO) claims that the risk of delivering of a child with a chromosomal pathology called trisomy is 1/385, 1/63 and 1/19 for a woman at the age of 30, 40 and 45 respectively. Moreover, a risk of lethal chromosomal mutations causing an intrauterine fetal death is even higher: aneuploidy (abnormal chromosome number) causes 25% of all miscarriage cases and, in particular, 50-60% of miscarriages in the first pregnancy trimester.

During an examination of women undergoing infertility treatment in IVF clinics it was proved that the number of euploid embryos (embryos with normal chromosome number) in women aged over 42 is not superior to 22%. Taking into account their reduced ovarian reserve, the chance of creating at least one mutations-free embryo after a superovulation stimulation is often inferior to 35%.

Embryo screening results*

Number of embryos on the 5th day Patients with at least one euploid embryo
(euploid embryos number)
Egg cells donors Under 35 35-39 40-42 Over 42
1-3 100%
(70%)
95%
(68%)
79%
(49%)
61%
(34%)
37%
(17%)
4-6 100%
(77%)
100%
(73%)
97%
(52%)
81%
(31%)
67%
(13%)
7-10 100%
(62%)
100%
(58%)
100%
(48%)
97%
(27%)
95%
(22%)

* Bluegnome’s calculations

PGD for chromosomal abnormalities significantly helps reduce the risk of miscarriages and failed IVF cycles.

A chromosome aberration analysis is performed in all 46 chromosomes with the help of CGH technique – a comparative genomic hybridization. One of the conclusive advantages of the technique is the opportunity to screen chromosome number in egg cells as well as in embryos.

If necessary, a 46 chromosome embryo screening can be performed along with a homogeneous diseases screening, and an HLA-compatibility test.

Indications to a PGD for chromosomal mutations in 46 chromosomes (ESHRE PGD Consortium’s recommendations):

  • mature reproductive age (women over 35);
  • several failed IVF cycles;
  • recurrent pregnancy loss;
  • male infertility caused by chromosomal mutations;
  • chromosomal mutations.