Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6.

Heimler syndrome (HS) is a rare recessive disorder characterized by sensorineural hearing loss (SNHL), amelogenesis imperfecta, nail abnormalities, and occasional or late-onset retinal pigmentation. We ascertained eight families affected by HS and, by using a whole-exome sequencing approach, identified biallelic mutations in PEX1 or PEX6 in six of them. Loss-of-function mutations in both genes are known causes of a spectrum of autosomal-recessive peroxisome-biogenesis disorders (PBDs), including Zellweger syndrome. PBDs are characterized by leukodystrophy, hypotonia, SNHL, retinopathy, and skeletal, craniofacial, and liver abnormalities. We demonstrate that each HS-affected family has at least one hypomorphic allele that results in extremely mild peroxisomal dysfunction. Although individuals with HS share some subtle clinical features found in PBDs, the diagnosis was not suggested by routine blood and skin fibroblast analyses used to detect PBDs. In conclusion, our findings define HS as a mild PBD, expanding the pleiotropy of mutations in PEX1 and PEX6.

Distribution of allelic and genotypic frequencies of NAT2 and CYP2E1 variants in Moroccan population.

BACKGROUND: Several pathogenesis and genetic factors influence predisposition to antituberculosis drug-induced hepatotoxicity (ATDH) especially for isoniazid (INH). However, the major susceptibility genes for ATDH are N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1). NAT2 gene determines the individual's acetylator status (fast, intermediate or slow) to metabolize drugs and xenobiotics, while CYP2E1 c1/c1 genotype carriers had an increased risk of ATDH. Polymorphisms of the NAT2 and CYP2E1 genes vary remarkably among the populations of different ethnic origins. The aim of this study was to determine, for the first time, the frequency of slow acetylators in Moroccan population by genotyping of NAT2 gene variants and determining the genotype c1/c1 for CYP2E1 gene, in order to predict adverse effects of Tuberculosis treatment, particularly hepatotoxicity. RESULTS: The frequencies of specific NAT2 alleles were 53%, 25%, 2% and 4% for NAT2*5, NAT2*6, NAT2*7 and NAT2*14 respectively among 163 Moroccan studied group. Genotyping of CYP2E1 gene, by real-time polymerase chain reaction using TaqMan probes, revealed frequencies of 98.5% for c1/c1 and 1.5% for c1/c2 among 130 Moroccan studied group. CONCLUSION: The most prevalent genotypes of NAT2 gene in Moroccans are those which encode slow acetylation phenotype (72.39%), leading to a high risk of ATDH. Most Moroccans are homozygous for c1 allele of CYP2E1 gene which aggravates hepatotoxicity in slow acetylators. This genetic background should be taken into account in determining the minimum dose of INH needed to treat Moroccan TB patients, in order to decrease adverse effects.

Homozygous nonsense mutation of WNT10B gene in a Moroccan family with split-hand foot malformation identified by exome sequencing: a case report.

Split-hand foot malformation (SHFM) is a clinically heterogeneous congenital limb defect affecting predominantly the central rays of hands and/or feet. The clinical expression varies in severity between patients as well between the limbs in the same individual. SHFM might be non-syndromic with limb-confined manifestations or syndromic with extra-limb manifestations. Isolated SHFM is a rare condition with an incidence of about 1 per 18,000 live born infants and accounts for 8-17 % of all limb malformations. To date, many chromosomal loci and genes have been described as associated with isolated SHFM, i.e., SHFM1 to 6. SHFM6 is one of the rarest forms of SHFM, and is caused by mutations in WNT10B gene. Less than ten pathogenic variants have been described. We have investigated a large consanguineous Moroccan family with three affected members showing feet malformations with or without split hand malformation phenotypes. Using an exome sequencing approach, we identified a homozygous nonsense variant p.Arg115* of WNT10B gene retaining thereby the diagnosis of SHFM6. This homozygous nonsense mutation identified by exome sequencing in a large family of split hand foot malformation highlights the importance of exome sequencing in genetically heterogeneous entities.

Novel splice site mutation in CNNM4 gene in a family with Jalili syndrome.

Jalili syndrome is a rare autosomal recessive genetic disease characterized by the association of amelogenesis imperfecta and cone-rod retinal dystrophy. This syndrome is caused by mutations in the CNNM4 gene. Different types of CNNM4 mutations have been reported; missense, nonsense, large deletions, single base insertion, and duplication. We used Sanger sequencing to analyze a large consanguineous family with three siblings affected with Jalili syndrome, suspected clinically after dental and ophthalmological examination. These patients are carrying a novel homozygous mutation in the splice site acceptor of intron 3 (c.1682-1G > C) in the CNNM4 gene. We compare the findings of the present family to those from literature, in order to further delineate Jalili syndrome.

Cytogenetic Investigation in a Group of Ten Infertile Men with Non-Obstructive Azoospermia: First Algerian 46, XX Syndrome.

BACKGROUND: In Algeria, the data on infertility and its various causes are rare. Recently, the introduction of assisted reproduction has allowed expecting that 300000 couples, which represent 7% of couples of reproductive age, face difficulty conceiving a child. Knowing that most idiopathic cases are likely to be due to chromosomal abnormalities, we aimed to investigate genetic defects by karyotype analysis in Algerian infertile men, using peripheral blood lymphocytes. METHODS: A cytogenetic study was conducted on 10 men from infertile couples by Karyotype analysis of R-banding performed by lymphocyte culture technique. Fluorescence in situ hybridization was performed and molecular abnormalities were investigated by polymerase chain reaction. Follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels were evaluated by immunoradiometric method. RESULTS: Chromosomal abnormalities were observed in 30% of the patients. We identified a homogenous Klinefelter syndrome patient with 47, XXY karyotype, a mosaic Klinefelter syndrome patient with 47, XXY/46, XY karyotype and a 46, XX male. Fluorescence in situ hybridization showed that the sex-determining region Y was translocated to the short arm of the X chromosome in patient with 46, XX chromosomal constitution and the presence of the SRY gene was confirmed by polymerase chain reaction and electrophoresis. CONCLUSION: The occurrence of chromosomal abnormalities in 30% of the infertile men strongly supports the inclusion of routine cytogenetic testing for diagnostic establishment and suitable counseling for couples seeking for assisted reproduction technologies.

NAT2 Genotypes in Moroccan Patients with Hepatotoxicity Due to Antituberculosis Drugs.

AIM: Isoniazid (INH) is the most effective drug used as a first-line tuberculosis (TB) treatment besides rifampicin, pyrazinamide, and ethambutol. It is also the most commonly associated with hepatotoxicity. Differences of toxicity induced by INH have been attributed to genetic variability of the N-acetyltransferase 2 (NAT2) gene which encodes a drug-metabolizing enzyme. The aim of this study was to characterize the acetylation profile of patients who developed hepatotoxicity after TB treatment by genotyping NAT2 polymorphisms. PATIENTS AND METHODS: This study included 42 Moroccan patients who developed hepatotoxicity after TB treatment and 163 Moroccan controls without TB. We genotyped four selected variants of the NAT2 gene (NAT2*5, NAT2*6, NAT2*7, and NAT2*14) by Sanger sequencing for patients and real-time polymerase chain reaction for controls. RESULTS: The majority of patients had NAT2 genotypes previously described as slow acetylators including NAT2*5/*5, NAT2*5/*6, NAT2*6/*6, and NAT2*6/*14 (78%) and none were genotyped as rapid acetylators. Controls were slow, intermediate, and rapid acetylators with frequencies of 72.39%, 21.48%, and 6.13%, respectively. CONCLUSION: There were no fast acetylator genotypes found among the patients having INH-hepatotoxicity. This finding suggests that the slow acetylator phenotype may contribute to the development of TB treatment hepatotoxicity.

Hyaline fibromatosis syndrome with mutation c.1074delT of the CMG2 gene: a case report.

INTRODUCTION: Juvenile hyaline fibromatosis and infantile systemic hyalinosis are variants of the same autosomal recessive syndrome; hyaline fibromatosis syndrome, characterized by papulonodular skin lesions, gingival hypertrophy, flexion contractures of joints, osteolytic bone lesions and stunted growth. Infantile systemic hyalinosis is distinguished from juvenile hyaline fibromatosis by its more severe phenotype, which includes hyaline deposits in multiple organs, recurrent infections and death within the first two years of life.Hyaline fibromatosis syndrome is due to mutations of the gene-encoding capillary morphogenesis protein 2 (CMG2). Cases have been reported in different countries but to the best of our knowledge, this is the first reported Moroccan patient with hyaline fibromatosis syndrome and carrying the CMG2 mutation. CASE PRESENTATION: We report the case of an eight-year-old Moroccan male patient with typical features of hyaline fibromatosis syndrome: multiple recurring subcutaneous tumors, gingival hypertrophy, joint contractures and other anomalies carrying a homozygous mutation in the CMG2 gene. The identification of the mutation in our patient allowed us to do a presymptomatic diagnosis in our patient's sister, a two-day-old newborn, who is carrying the familial mutation in the heterozygous state. Early recognition of this condition is important for genetic counseling and early treatment. CONCLUSIONS: Hyaline fibromatosis syndrome might be underdiagnosed. Molecular diagnosis will help clinicians and geneticists, firstly to conduct genetic counseling, prenatal diagnosis and early treatment, and secondly to gain better understanding of the disease and genotype-phenotype correlations.

Novel nonsense mutation of BRCA2 gene in a Moroccan man with familial breast cancer.

BACKGROUND: Breast cancer is the most common cancer in women worldwide. About 5 to 10% of cases are due to an inherited predisposition in two major genes, BRCA1 and BRCA2, transmitted as an autosomal dominant form. Male breast cancer is rare and is mainly due to BRCA2 than BRCA1 germline mutations. OBJECTIVE: Molecular study of BRCA2 gene in man with familial breast cancer. METHODS: PCR and direct sequencing of BRCA2 gene. RESULTS: Identification of novel heterozygous germline mutation c.6428C>A ; p.Ser2143Stop of BRCA2 gene.