Frequency of Epidermal Growth Factor Receptor Gene Variant in Roma Population

Introduction

Epidermal growth factor receptor (EGFR) is a member of transmembrane tyrosine kinase receptor family, important in tissue growth and maintenance. Neonatal inflammatory skin and bowel disease 2, caused by pathogenic variant in EGFR gene, was first described in 2014 by Campbell et al. (2014). Since then, variant p.GLY428Asp (c.1283G-A) was found in homozygous state in all but one patient (Hayashi et al., 2018) with this syndrome.

The variant works in recessive manner. It suppresses EGFR-dependent activation and downstream signaling and results in a loss of function as well as loss of plasma membrane localization (Campbell et al., 2014). Variant p.GLY428Asp was described almost exclusively in Roma, and it is considered to be a founder mutation for this ethnic group (Ganetzky et al., 2015; Mazurova et al., 2020). Patients present with intrauterine growth restriction and severe skin lesions with thin, translucent, desquamative skin. Recurrent skin infections result in life-threatening sepsis, feeding difficulties, with an intolerance of solids and attacks of diarrhea, vomiting and dehydration cause an early death in neonatal or early infantile period (Alruwaithi and Sherlock, 2018; Campbell et al., 2014; Earl et al., 2020; Ganetzky et al., 2015; Labbouz et al., 2023; Lemos et al., 2021; Mazurova et al., 2020; Santos et al., 2022).

The only comprehensive cohort of patients described so far apart from single cases or sibling pairs was a group of 18 Roma children from Slovak and Czech Republic (Mazurova et al., 2020). This leads to a conclusion that the frequency of p.GLY428Asp is high in the Roma population of these countries. The population of Roma in Slovakia is around 400,000 individuals, one of the largest in Europe. Slovak Roma form very endogamous, isolated communities, with very high inbreeding coefficient. The aim of this article is to supplement the picture of Roma predisposition to neonatal inflammatory skin and bowel disease by establishing the frequency of p.GLY428Asp variant in EGFR gene in the Roma population in Slovakia.

Methods

This study was carried out on a randomly selected population sample of 1321 unrelated individuals aged 18-71 years (average 40.12 ± 13.24 years), 592 (44.81%) were men, 729 (55.19%) women. The subjects were apparently healthy adult volunteer individuals of Roma origin from Slovakia. Ethnicity was determined based on self-identification. Informed consent was signed by every participant. The protocols were approved by the Ethics Committee for Research of University of Presov (No. ECUPO82023PO). Genomic DNA was extracted from buccal swabs using a commercial kit (ReliaPrep™ gDNA Tissue Miniprep System). Variant p.GLY428Asp (c.1283G-A) in EGFR gene was tested by real-time PCR (AB7500 fast) using TaqMan™ probes.

Results and Discussion

Genotyping of 1321 individuals of Roma origin from Slovakia revealed 35 carriers for the p.GLY428Asp variant in EGFR gene, thus estimating the carrier frequency to be 2.65% and allele frequency 1.32%. Variant in homozygous state was not detected. The observed frequency is high. Together with the fact that a large number of cases with neonatal inflammatory skin and bowel disease 2 were diagnosed in Slovakia and Czech Republic (Mazurova et al., 2020), this represents strong evidence of the high incidence of this disease among Roma in Slovakia. The only Roma group for which data are available are Iberian Roma. The Iberian Roma genetic variant server reports a frequency of this variant to be 0.008% (Mavillard et al., 2023). The frequency in all general populations in public databases not specialized on Roma is less than 0.001% (Ensemble Human; NCBI).

Roma (Gypsies) form a population, with unique origin and history marked by several factors (bottleneck during migration, founder effect, splitting into numerous subgroups, limited degree of admixture from surrounding populations), that make this ethnic group a valuable source of genetic information especially in searching for causes of rare recessively inherited conditions (Morar et al., 2004). In the past few years, the list of mutations associated with Roma population was extended by several novel variants discovered (Bradinova et al., 2022; Cabrera-Serrano et al., 2018; Mavillard et al., 2021; van der Knoop et al., 2022). These variants are in most cases found in children of consanguineous parents and are (so far) restricted to a single case or low number of cases in particular country. However, based on our knowledge of Roma history, as well as on previous experiences, these mutations are very likely to be present, often in a high frequency, in Roma populations in other countries as well. Since these mutations are usually a cause of severe disease, it is necessary to know their occurrence in Roma populations to identify a need to implement them into diagnostic procedures and potentially to screening programs. Many diseases now known to be linked to Roma ethnicity were previously under diagnosed, or left without diagnosis completely, due to genetic tests aimed on general populations. Yet, after the knowledge of Roma specific variant was spread and diagnostic procedure evaluated, it was found in many cases that the variant is very common in Roma and number of diagnosed cases has jumped up (Ivanov et al., 2023; Stiburkova et al., 2021).

Conclusion

NISBD2 caused by variant in EGFR gene is a very rare inherited disorder, reported until now worldwide only in 27 patients mostly of Roma origin. In Slovakia, we report 2.65% carrier frequency, which together with a significant number of patients reported previously proves p.GLY428Asp variant in EGFR gene to be of major concern in Slovak Roma health. Detection of frequency of this variant in other countries with significant Roma population and proper inclusion into diagnostics is needed.