• Periklis Makrythanasis, Mari Nelis, Federico A Santoni, Michel Guipponi, Anne Vannier, Frédérique Béna, Stefania Gimelli, Elisavet Stathaki, Samia Temtamy, André Mégarbané, Amira Masri, Mona S Aglan, Maha S Zaki, Armand Bottani, Siv Fokstuen, Lorraine Gwanmesia, Konstantinos Aliferis, Mariana Bustamante Eduardo, Georgios Stamoulis, Stavroula Psoni, Sofia Kitsiou-Tzeli, Helen Fryssira, Emmanouil Kanavakis, Nasir Al-Allawi, Abdelaziz Sefiani, Sana' Al Hait, Siham C Elalaoui, Nadine Jalkh, Lihadh Al-Gazali, Fatma Al-Jasmi, Habiba Chaabouni Bouhamed, Ebtesam Abdalla, David N Cooper, Hanan Hamamy, and Stylianos E Antonarakis.
• Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland; Service of Genetic Medicine, University Hospitals of Geneva, Geneva, Switzerland.
• Hum. Mutat. 2014 Oct 1; 35 (10): 1203-10.

AbstractRare, atypical, and undiagnosed autosomal-recessive disorders frequently occur in the offspring of consanguineous couples. Current routine diagnostic genetic tests fail to establish a diagnosis in many cases. We employed exome sequencing to identify the underlying molecular defects in patients with unresolved but putatively autosomal-recessive disorders in consanguineous families and postulated that the pathogenic variants would reside within homozygous regions. Fifty consanguineous families participated in the study, with a wide spectrum of clinical phenotypes suggestive of autosomal-recessive inheritance, but with no definitive molecular diagnosis. DNA samples from the patient(s), unaffected sibling(s), and the parents were genotyped with a 720K SNP array. Exome sequencing and array CGH (comparative genomic hybridization) were then performed on one affected individual per family. High-confidence pathogenic variants were found in homozygosity in known disease-causing genes in 18 families (36%) (one by array CGH and 17 by exome sequencing), accounting for the clinical phenotype in whole or in part. In the remainder of the families, no causative variant in a known pathogenic gene was identified. Our study shows that exome sequencing, in addition to being a powerful diagnostic tool, promises to rapidly expand our knowledge of rare genetic Mendelian disorders and can be used to establish more detailed causative links between mutant genotypes and clinical phenotypes.© 2014 WILEY PERIODICALS, INC.

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