Diagnosis of Laron syndrome using monoplex-polymerase chain reaction technology with a whole-genome amplification template: A case report

Abstract

BACKGROUND

Laron syndrome (LS) is an autosomal recessive hereditary condition affecting only 1/1000000 births. The cause is associated with mutations in the growth hormone (GH) receptor (GHR), leading to GH insensitivity. LS patients typically present with severe growth retardation, obesity, and abnormal sexual maturation. Currently, LS diagnosis is performed post-delivery. Therefore, we assessed the efficiency of Pre-implantation Genetic Testing (PGT) coupled with monoplex-polymerase chain reaction (PCR) technology for detecting this monogenic disease in embryos from a couple confirmed as LS heterozygous carriers

CASE SUMMARY

The couple LS-carriers were confirmed by the presence of a first child born with LS. The couple underwent a standard in vitro fertilization (IVF) protocol. DNA was collected from trophectoderm cells from day 5 embryos. Whole genome amplification (WGA) was performed using a Sureplex DNA Amplification System and analyzed by PCR, targeting the deletion of the exons 5 and 6 in the GHR gene as well as PGT by Next-generation Sequencing (Illumina). Eleven embryos were collected and analyzed. 27.3% were the wild type for GHR, 45.5% were heterozygotes, and 18.2% homozygous mutants. One embryo yielded no results. Three 2-embryos transfers were performed; 2 normal homozygous and four heterozygous carriers were selected for transfer. The first two transfers were unsuccessful, whereas the final transfer with two heterozygous embryos resulted in clinical pregnancy. The genomic composition of the fetus was verified, applying the same techniques using amniocytes, extracted after 21 wk of the ongoing pregnancy. The fetus was confirmed as GHR deletion in exon 5-6, carrier. A non-affected baby was born.

CONCLUSION

Here, we present a case demonstrating that using WGA as a template in addition to PCR targeting specific gene regions, exons 5 and 6 on the GHR gene, could identify LS carrier embryos. This provides evidence that WGA and PCR serve as an excellent tool to detect this specific monogenic disease in IVF embryos, thus allowing selection of candidate embryos for transfer successfully when a specific inherited genetic mutation/disease is suspected.

Keywords: Growth hormone insensitivity, Growth hormone receptor mutations, Intragenic deletions, Molecular diagnosis, Embryo diagnosis, Laron syndrome, Case report

Core tip: Laron syndrome (LS) is a low prevalent, autosomal recessive hereditary disorder affecting the Jewish population; however, when LS is expected, genetic testing is required. This case study demonstrates that by using monoplex-polymerase chain reaction (PCR) during Pre-implantation Genetic Diagnosis, we were able to accurately identify mutations in the growth hormone receptor (GHR). Here, we show that, in Mexico, the cause of LS was the deletion of the exons 5 and 6 in the GHR gene; moreover, we were able to select an embryo, which produced an LS negative fetus. This study provides evidence that monoplex-PCR can serve as an excellent tool to detect diseases during in vitro fertilization.