Altuğ Koç

An unexpected finding in a child with neurological problems: mosaic ring chromosome 18

Major neurological disorders may accompany rare chromosomal abnormalities. As an example of this rare condition, we present a case with microcephaly, mental retardation, developmental delay, hyperactivity, stereotypic movements, seizures and dysmorphic facial appearance in whom a mosaic ring chromosome 18 was found [45,XX,-18/46,XX,r(18)/46,XX,dicr(18)]. Although ring chromosome 18 phenotype has been known for a long time, this is the third reported patient with a dicentric ring chromosome 18 mosaicism. The presented case will contribute to the identification of the genotype-phenotype correlation in chromosome 18 anomalies.

A Novel Mutation in the SLC19A2 Gene in a Turkish Female with Thiamine-responsive Megaloblastic Anemia Syndrome

Reported here is a 2-year-old girl who was diagnosed to have thiamine-responsive megaloblastic anemia during evaluations for her bilateral neurosensorial deafness. Besides reporting a new mutation on the gene SLC19A2 for the first time in the literature, we highlight the recognition of this syndrome--when megaloblastic anemia and diabetes mellitus coexists--and the role of thiamine replacement for the treatment of both disorders.

The Apolipoprotein E Gene and Taq1A Polymorphisms in Childhood Obesity

Obesity is a multifactorial disease that is influenced by genetic and environmental factors. The apolipoprotein E (Apo E) polymorphism has been reported to influence some lipid profile abnormalities associated with obesity in childhood. In this study, the relationship between the Apo E gene and Taq1A polymorphisms with childhood obesity has been studied. Regarding the Apo E genotypes, e3/4 was the most frequent in both the patient and control groups. Further, there was a significance between the Apo E genotypes with low density lipoprotein and total cholesterol levels. However, no relationship was found between the Taq1A polymorphism and obesity. In conclusion, polygenic inheritance should be kept in mind when dealing with childhood obesity.

The importance of systematic genetic approach to familial schizophrenia cases and discussion of cryptic mosaic X chromosome aneuploidies in schizophrenia pathogenesis

Abstract Objective. The aim of this study is to contribute to the understanding of schizophrenia genetics by using efficient algorithmic examination techniques including dysmorphic examination, karyotyping, and Fluoresence in situ hybridization (FISH). Methods. In this study we have investigated 20 familial schizophrenia patients from Turkey who had an affected first-degree relative. Dysmorphic examination of the schizophrenia cases and their relatives have been performed. High resolution banding (HRB), specific centromeric, subtelomeric and 22q11.2 region FISH probes were used for genotyping of patients. Results. Dysmorphic examination revealed ear, palate, nose, columella anomalies, and obesity in contributing patients, and the pale skin was noticed. The medical histories and clinical findings of two schizophrenia twins were almost identical. HRB study demonstrated the presence of 46,XX[55]/47,XXX[4]/48,XXXX[1] constitution in a paranoid schizophrenia case and 46,XX[67]/45,X[5] karyotype in her mother. FISH studies aiming subtelomeric chromosomal regions revealed no rearrangements and 22q11.2 regions were intact in all of the patients. Conclusions. The parental gonadal mosaicism lying at the origin of the mitotic aneuploidy may be the reason for mosaic X chromosome aneuploidies in our mother–daughter schizophrenia couple. Mosaic X chromosome aneuploidies may accompany schizophrenia cases and may contribute to pathogenesis of familial schizophrenia.

Prenatal diagnosis of mosaic ring 22 duplication/deletion with terminal 22q13 deletion due to abnormal first trimester screening and choroid plexus cyst detected on ultrasound

We report a rare case of mosaic ring chromosome 22 duplication/deletion in a fetus for whom karyotype analysis was required because of an abnormal finding in the maternal serum screening test and a choroid plexus cyst detected on prenatal ultrasound. Additional prenatal study of the amniotic fluid by fluorescence in situ hybridization was performed and the terminal 22q13.3 deletion was detected on ring chromosome. The final karyotype was 45,XX,‐22[3]/46,XX,r(22)(p11q13.2)[63]/46,XX,idicr(22)(p11q13.2;p11q13.2)[2]dn.ishder(22)(N25+, ARSA‐, ter‐). The pegnancy was terminated. Cytogenetic analysis of the intracardiac blood also revealed ring 22 mosaicism with only one metaphase spread with idicr(22) as the unstable isodicentric rings are subsequently lost from most cells. We discuss the prenatal diagnosis of this rare condition.

Targeted Next Generation Sequencing of MLH1, MSH2, and MSH6 Genes in Patients with Endometrial Carcinoma <50 Years of Age

Background: Lynch syndrome is an inherited cancer disorder that causes an increased lifetime risk of various types of cancers. Endometrial cancer is the most common extracolonic cancer in Lynch syndrome. Guidelines recommend that patients with endometrial cancer younger than 50 years of age should be evaluated for Lynch syndrome. Molecular analysis of the mismatch repair genes and EPCAM gene is required for a definitive diagnosis of Lynch syndrome. Aims: To report the mutation analysis of mismatch repair genes using targeted next-generation sequencing in endometrial cancer diagnosed patients <50 years of age. Study Design: Retrospective cross-sectional study. Methods: Seventy-nine endometrial cancer diagnosed patients <50 years of age underwent genetic counseling. They were selected among 1094 consecutive endometrial cancer patients between 2006 and 2017. Molecular analysis of MLH1, MSH2, and MSH6 genes was performed in 79 patients by using next-generation sequencing. Deletion/duplication analysis of mismatch repair genes and EPCAM gene was also performed in 79 patients by using the multiplex ligation-dependent probe amplification method. Results: Germline testing of mismatch repair genes was performed in 79 endometrial cancer patients. Lynch syndrome was confirmed in 4 patients (5%; 4/79). A total of 14 variants (6 in MSH2, 5 in MLH1, 3 in MSH6 genes) were found in 14 patients. Four variants were assessed as pathogenic/likely pathogenic, and 10 variants were assessed as variants of uncertain significance. Conclusion: Lynch syndrome should be investigated in patients diagnosed with endometrial cancer that are less than 50 years of age due to the increased lifetime risk of developing cancer.