Autozygosity-driven genetic diagnosis in consanguineous families from Italy and the Greater Middle East

Flavia Palombo, Claudio Graziano, Nadia Al Wardy, Nayereh Nouri, Caterina Marconi, Pamela Magini, Giulia Severi, Chiara La Morgia, Gaetano Cantalupo, Duccio Maria Cordelli, Simone Gangarossa, Mohammed Nasser Al Kindi, Mazin Al Khabouri, Mansoor Salehi, Elisa Giorgio, Alfredo Brusco, Francesco Pisani, Giovanni Romeo, Valerio Carelli, Tommaso PippucciMarco Seri

Research output: Contribution to journalArticlepeer-review

Abstract

Autozygosity-driven exome analysis has been shown effective for identification of genes underlying recessive diseases especially in countries of the so-called Greater Middle East (GME), where high consanguinity unravels the phenotypic effects of recessive alleles and large family sizes facilitate homozygosity mapping. In Italy, as in most European countries, consanguinity is estimated low. Nonetheless, consanguineous Italian families are not uncommon in publications of genetic findings and are often key to new associations of genes with rare diseases. We collected 52 patients from 47 consanguineous families with suspected recessive diseases, 29 originated in GME countries and 18 of Italian descent. We performed autozygosity-driven exome analysis by detecting long runs of homozygosity (ROHs > 1.5 Mb) and by prioritizing candidate clinical variants within. We identified a pathogenic synonymous variant that had been previously missed in NARS2 and we increased an initial high diagnostic rate (47%) to 55% by matchmaking our candidate genes and including in the analysis shorter ROHs that may also happen to be autozygous. GME and Italian families contributed to diagnostic yield comparably. We found no significant difference either in the extension of the autozygous genome, or in the distribution of candidate clinical variants between GME and Italian families, while we showed that the average autozygous genome was larger and the mean number of candidate clinical variants was significantly higher (p = 0.003) in mutation-positive than in mutation-negative individuals, suggesting that these features influence the likelihood that the disease is autozygosity-related. We highlight the utility of autozygosity-driven genomic analysis also in countries and/or communities, where consanguinity is not widespread cultural tradition.

Original languageEnglish
Pages (from-to)1429-1441
Number of pages13
JournalHuman Genetics
Volume139
Issue number11
DOIs
Publication statusPublished - Nov 1 2020

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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