Autoimmune polyendocrinopathy syndrome type 1 (APS1) is characterized by the presence of at least two out of three clinical features, which include Addison's disease, hypoparathyroidism, and chronic mucocutaneous candidiasis. This disorder is caused by mutations in the AIRE (autoimmune regulator) gene. While several AIRE mutations have been described in APS1 patients of various ethnic origins, the genetic cause of APS1 in Arab patients requires further investigation. This study describes seven Arab families, in which 18 patients had APS1. In addition to the cardinal features of APS1, some patients exhibited alopecia, diabetes mellitus, nephrocalcinosis and other phenotypes associated with APS1. DNA sequencing of the AIRE gene of patients from this study identified four novel and one recurrent mutation. These mutations likely result in loss of AIRE function in the patients. In addition, it was noted that the non-pathogenic c.834C> G mutation (rs1800520, encoding for p.Ser278Arg) occurs with high incidence in the AIRE gene of Arab individuals. Furthermore, this investigation demonstrates inflammation of the hair follicles in APS1 patients with alopecia universalis. We conclude that Arab APS1 patients carry novel and recurrent mutations in the AIRE gene.

Autosomal recessive severe congenital neutropenia (SCN) results from a maturation arrest of granulopoiesis at the level of promyelocytes and apoptosis of myeloid cells. In SCN patients, mutations have been described in the HAX1 gene. Most of the SCN patients who carry nonsense mutations that are common to both transcript variants of the HAX1 gene also exhibit neurological deficits. This study describes an SCN patient with neurological manifestations including daily episodes of atonic seizures, learning disabilities, and developmental delay. Sequencing of the HAX1 gene of this SCN patient identified a novel nonsense c.463_464insC homozygous mutation in exon 3, which is common to both transcript variants of the gene. This mutation encodes for a p.Gln155ProfsX14 change and causes premature truncation of the HAX1 protein. Neutrophils isolated from the patient exhibited spontaneous apoptosis and loss of inner mitochondrial membrane potential, which were further enhanced upon treatment with hydrogen peroxide. This study adds to the spectrum of novel HAX1 gene mutations and disease manifestations in ethnically distinct SCN patients. Our report describes the only nonsense mutation in the HAX1 gene present in SCN patients of Arab origin.

Homocystinuria due to cystathionine beta synthase (CBS) deficiency results in elevated plasma homocysteine and methionine levels, which are associated with multiple organ pathologies, including vascular, respiratory, musculoskeletal, nervous, and ocular tissues. This autosomal recessive disorder is caused by homozygous or compound heterozygous mutations in the CBS gene encoding for the CBS. Although homocystinuria is observed in Arab and North African patients, their clinical presentations have not been described and molecular causes remained largely uninvestigated. In this study, we describe the clinical presentations of 22 homocystinuria patients from 13 Saudi Arabian families and 1 North African Sudanese family. Cardinal biochemical features of homocystinuria manifested in all patients, but heterogeneity of expression was observed for other associated phenotypes. One patient developed Legg-Calvé-Perthes disease that has not been previously described in homocystinuria. In the Saudi families, a novel nonsense mutation, p.Trp323X, and recurrent p.Arg336Cys and p.Gly153Arg mutations were identified in the CBS gene. The p.Trp323X mutation was found in 10 of the 13 unrelated Saudi families. In the Sudanese family, the p.Thr257Met mutation in the CBS gene, previously described in Italian and Spanish patients, was found. This study shows that the spectrum of CBS gene mutations in Saudi homocystinuria patients is quite different than the Arab patients from Qatar and Israel. This study is the only detailed phenotypic and genetic depiction of homocystinuria patients from Saudi Arabia and Sudan. The data are useful for diagnosis and management of Saudi patients.

BACKGROUND AND OBJECTIVESL-2-hydroxyglutaric aciduria is a neurometabolic disorder with autosomal recessive mode of inheritance in which patients exhibit elevated L-2-hydroxyglutaric acid in body fluids, central nervous system manifestations, and increased risk of brain tumor formation. Mutations in L2HGDH gene have been described in L-2-hydroxyglutaric aciduria patients of different ethnicities. The present study was conducted to perform a detailed clinical, imaging and genetic analysis.DESIGN AND SETTINGSA cross-sectional clinical genetic study of 16 L-2-hydroxyglutaric aciduria patients from 4 Arab consanguineous families examined at the metabolic clinic of the hospital.PATIENTS AND METHODSGenomic DNA was isolated from the blood of 12 patients and 10 unaffected family members, and the L2HGDH gene was sequenced. DNA sequences were compared to the L2HGDH reference sequence from GenBank.RESULTSAll patients exhibit characteristic clinical, biochemical, and imaging features of L-2-hydroxyglutaric aciduria, and 4 patients exhibited increased incidence of brain tumors. The sequencing of the L2HGDH gene revealed the c.1015delA, c.1319C>A, and c.169G>A mutations in these patients. These mutations encode for the p.Arg339AspfsX351, p.Ser440Tyr, and p.Gly57Arg changes in the L2HGDH protein, respectively. The c.169G>A mutation, which was shown to have a common origin in Italian and Portuguese patients, was also discovered in Arab patients. Finding of the homozygous c.159T SNP associated with the c.169G>A mutation in Arab patients points to an independent origin of this mutation in Arab population.CONCLUSIONThe detailed description of clinical manifestations and L2HGDH mutation in this study is useful for diagnosis of L-2-hydroxyglutaric aciduria in Arab patients. While reoccurrence of an L2HGDH mutation in L-2-hydroxyglutaric aciduria patients of different ethnicity is extremely rare, the c.169G mutation has an independent origin in Arab patients. It is likely that this mutation may also be present in patients of other ethnicities.