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Kimia Kahrizi

Publications and source records attributed to Kimia Kahrizi.

8 recordsLinked to original sources
PubMed2006

Homozygosity mapping in consanguineous families reveals extreme heterogeneity of non-syndromic autosomal recessive mental retardation and identifies 8 novel gene loci.

Autosomal recessive gene defects are arguably the most important, but least studied genetic causes of severe cognitive dysfunction. Homozygosity mapping in 78 consanguineous Iranian families with nonsyndromic autosomal recessive mental retardation (NS-ARMR) has enabled us to determine the chromosomal localization of at least 8 novel gene loci for this condition. Our data suggest that in the Iranian population NS-ARMR is very heterogeneous, and they argue against the existence of frequent gene defects that account for more than a few percent of the cases.

Adult↗
PubMed2006

Sensorineural deafness and male infertility: a contiguous gene deletion syndrome.

BACKGROUND: Syndromic hearing loss that results from contiguous gene deletions is uncommon. Deafness-infertility syndrome (DIS) is caused by large contiguous gene deletions at 15q15.3. METHODS: Three families with a novel syndrome characterised by deafness and infertility are described. These three families do not share a common ancestor and do not share identical deletions. Linkage was established by completing a genome-wide scan and candidate genes in the linked region were screened by direct sequencing. RESULTS: The deleted region is about 100 kb long and involves four genes (KIAA0377, CKMT1B, STRC and CATSPER2), each of which has a telomeric duplicate. This genomic architecture underlies the mechanism by which these deletions occur. CATSPER2 and STRC are expressed in the sperm and inner ear, respectively, consistent with the phenotype in persons homozygous for this deletion. A deletion of this region has been reported in one other family segregating male infertility and sensorineural deafness, although congenital dyserythropoietic anaemia type I (CDAI) was also present, presumably due to a second deletion in another genomic region. CONCLUSION: We have identified three families segregating an autosomal recessive contiguous gene deletion syndrome characterised by deafness and sperm dysmotility. This new syndrome is caused by the deletion of contiguous genes at 15q15.3.

Base Sequence↗
PubMed2005

SNP array-based homozygosity mapping reveals MCPH1 deletion in family with autosomal recessive mental retardation and mild microcephaly.

Very little is known about the molecular basis of autosomal recessive MR (ARMR) because in developed countries, small family sizes preclude mapping and identification of the relevant gene defects. We therefore chose to investigate genetic causes of ARMR in large consanguineous Iranian families. This study reports on a family with six mentally retarded members. Array-based homozygosity mapping and high-resolution microarray-based comparative genomic hybridization (array CGH) revealed a deletion of approximately 150-200 kb, encompassing the promoter and the first six exons of the MCPH1 gene, one out of four genes that have been previously implicated in ARMR with microcephaly. Reexamination of affected individuals revealed a high proportion of prematurely condensed chromosomes, which is a hallmark of this condition, but in spite of the severity of the mutation, all patients showed only borderline to mild microcephaly. Therefore the phenotypic spectrum of MCPH1 mutations may be wider than previously assumed, with ARMR being the only consistent clinical finding.

Adolescent↗
PubMed2005

GJB2 mutations: passage through Iran.

Hereditary hearing loss (HHL) is a very common disorder. When inherited in an autosomal recessive manner, it typically presents as an isolated finding. Interestingly and unexpectedly, in spite of extreme heterogeneity, mutations in one gene, GJB2, are the most common cause of congenital severe-to-profound deafness in many different populations. In this study, we assessed the contributions made by GJB2 mutations and chromosome 13 g.1777179_2085947del (the deletion more commonly known as del (GJB6-D13S1830) that includes a portion of GJB6 and is hereafter called Delta(GJB6-D13S1830)) to the autosomal recessive non-syndromic deafness (ARNSD) genetic load in Iran. Probands from 664 different nuclear families were investigated. GJB2-related deafness was found in 111 families (16.7%). The carrier frequency of the 35delG mutation showed a geographic variation that is supported by studies in neighboring countries. Delta(GJB6-D13S1830) was not found. Our prevalence data for GJB2-related deafness reveal a geographic pattern that mirrors the south-to-north European gradient and supports a founder effect in southeastern Europe.

Connexin 26↗
PubMed2004

Hb Dhonburi (Neapolis) [beta126(H4)Val-->Gly] identified in a family from northern Iran.

Thalassemias are the most common hereditary diseases in Iran, resulting from synthesis defects in one or more hemoglobin (Hb) subunits. The majority of patients suffer from beta-thalassemia (thal), but cases with microcytic hypochromic anemia and normal electrophoretic patterns are suspected to have alpha- or silent beta-thal. A family from the northern part of Iran, an area highly prevalent for thalassemias, was referred to us for prenatal diagnosis. The hematological data of the father indicated a pattern of beta-thal minor. Reverse hybridization analysis for the most common beta-globin mutations identified IVS-II-1 (G-->A) in the heterozygous state. The maternal laboratory data indicated a case more compatible with alpha-thal. Iron deficient anemia was ruled out, and common alpha-thal point mutations and deletions were investigated. As no mutation was detected, chain synthesis was performed and showed an alpha/beta chain ratio of 2.1, that was in the range of beta-thal minor. DNA sequencing of the entire beta-globin gene identified a heterozygous GTG-->GGG (Val-->Gly) mutation at codon 126, also known as Hb Dhonburi (Neapolis). Prenatal diagnosis of the fetal DNA showed the absence of the IVS-II-1 and codon 126 anomalies. This result demonstrates the importance of screening of individuals with mild microcytic hypochromic anemia for both alpha- and silent beta-thal mutations.

Family↗
PubMed2003

The Iranian Human Mutation Gene Bank: a data and sample resource for worldwide collaborative genetics research.

As Human Genome Project exploration continues, the necessity of having a broader spectrum of genomic DNA material from different nationalities to study various aspects of hereditary disease becomes more obvious. The existence of high genetic polymorphism within and between different communities in the world makes it necessary for the gene hunters to investigate many different populations. Iran, a large country with close to 66 million people, is a land of different nationalities, tribes, and religions that offers a highly heterogeneous gene pool to the genetics researcher. The purity of many different races in this country has been highly conserved by geographical borders and by an ancient culture that has always encouraged intrafamilial marriages. All these have created a population that is remarkably heterogeneous yet high in consanguinity rate. During the last five years of investigation we have established a DNA bank, the Iranian Human Mutation Gene Bank (www.IHMGB.com), which contains all genetic diseases studied in Iran that have the Mendelian mode of inheritance. Some of the samples are assigned to common or novel mutations and others belong to patients with clinical profiles associated with particular genetic diseases but undefined mutation. This bank stores samples of DNA from the patient and his/her first-degree relatives together with a comprehensive pedigree and clinical profile for each sample. To facilitate collaboration with other scientists around the world with the same interests, we decided to present our experimental projects online. This DNA bank provides opportunities for us to collaborate with scientists outside Iran. It offers a sample resource to research scientists around the world, at no charge, for the purpose of investigating the various aspects of genetic disorders from prenatal diagnosis to gene structure and function. It is strongly stressed that no commercial benefit is involved in the establishment of this DNA bank and the DNA samples are free of charge. However, to meet our goals and to respect ethical values, DNA samples can only be used under certain conditions stated in the User Consent Form.

Consanguinity↗
PubMed2002

GJB2 mutations in Iranians with autosomal recessive non-syndromic sensorineural hearing loss.

Hereditary hearing loss (HHL) is an extremely common disorder. About 70% of HHL is non-syndromic, with autosomal recessive forms accounting for approximately 85% of the genetic load. Although very heterogeneous, the most common cause of HHL in many different world populations is mutations of GJB2, a gene that encodes the gap junction protein connexin 26 (Cx26). This study investigates the contribution of GJB2 to the autosomal recessive non-syndromic deafness (ARNSD) load in the Iranian population. One hundred sixty eight persons from 83 families were studied. GJB2-related deafness was diagnosed in 9 families (4, 35delG homozygotes; 3, 35delG compound heterozygotes; 1, W24X homozygote; 1, non-35delG compound heterozygote). The carrier frequency of the 35delG allele in this population was approximately 1% (1/83). Because the relative frequency of Cx26 mutations is much less than in the other populations, it is possible that mutations in other genes play a major role in ARNSD in Iran.

Connexin 26↗