About 30%–40% of patients with pheochromocytoma (PCC) and paraganglioma (PGL) have underlying germline mutations in certain susceptibility genes despite absent family history of these tumors. Here, we present mutational profile of 101 such patients with PCC/PGL (PPGL) from the highly consanguineous population of Saudi Arabia. Results: Of 101 cases with PPGL, 37/101 (36.6%) had germline mutations. Mutations were detected in 30 cases by PCR and direct Sanger sequencing and in 7 additional cases by NGS. The most commonly mutated gene was SDHB (21/101 cases, 20.8%) and the most common SDHB mutation was c.268C>T, p.R90X occurring in 12/21 (57%) cases. Mutations also occurred in SDHC (4/101, 3.96%), SDHD (3/101, 3%), VHL (2/101, 2%) and MAX (2/101, 2%) genes. The following genes were mutated in 1 patient each (1%), RET, SDHA, SDHAF2, TMEM127 and NF1. Metastatic PPGL occurred in 6/21 cases (28.6%) with SDHB mutations and in 1 case with SDHAF2 mutation. Patients and Methods: DNA was isolated from peripheral blood (53 patients) or from non-tumorous formalin fixed paraffin embedded (FFPE) tissue (48 patients). PCR and direct Sanger sequencing of RET, SDHx, VHL, MAX and TMEM127 genes were performed. Cases without mutations were subjected to whole exome sequencing using next generation sequencing (NGS). Conclusion: About 37% of PPGL without family history of such tumors harbor germline mutations. The most commonly mutated gene is SDHB followed by SDHC, SDHD, VHL, MAX and rarely RET, SDHA, SDHAF2, TMEM127 and NF1. SDHB mutations were associated with metastatic PPGL in more than a quarter of cases.

Different types of mutations have been reported in patients with hemophilia A. Although about half of all severe factor VIII deficiencies are caused by gene rearrangements (inversions) involving intron 22 in F8, other mutations such as point mutation, large deletions and insertions had been reported. We report the result of the first molecular testing for or F8 mutations from Saudi Arabia. A cohort of 22 men with hemophilia A was studied for F8 mutations. All patients were tested for factor VIII coagulant activity and inhibitors. Peripheral blood samples were used for DNA extraction followed by PCR detection of intron 22 inversion and all samples tested negative were screened for other F8 mutations. The patient's age ranged between 4 and 37 years. All patients except two siblings had severe hemophilia A. Only two patients out of 22 developed inhibitors with no obvious relation to the genotype. F8 Intron 22 inversion was detected in 10 patients (50%) of severe cases. Additionally, five point mutations and one deletion/insertion involving different exons were detected. All identified mutations were associated with severe phenotype except for one, which was associated with mild phenotype of hemophilia. This is the first report of molecular genotype of hemophilia A in the Saudi population and one of the few for Arab population. We had confirmed the incidence of Inversion 22 in severe hemophilia. We are reporting two novel mutations in F8, which can be used for carrier detection and prenatal genetic diagnosis (PGD).