Evolution of genetic techniques: past, present, and beyond.

Genetics is the study of heredity, which means the study of genes and factors related to all aspects of genes. The scientific history of genetics began with the works of Gregor Mendel in the mid-19th century. Prior to Mendel, genetics was primarily theoretical whilst, after Mendel, the science of genetics was broadened to include experimental genetics. Developments in all fields of genetics and genetic technology in the first half of the 20th century provided a basis for the later developments. In the second half of the 20th century, the molecular background of genetics has become more understandable. Rapid technological advancements, followed by the completion of Human Genome Project, have contributed a great deal to the knowledge of genetic factors and their impact on human life and diseases. Currently, more than 1800 disease genes have been identified, more than 2000 genetic tests have become available, and in conjunction with this at least 350 biotechnology-based products have been released onto the market. Novel technologies, particularly next generation sequencing, have dramatically accelerated the pace of biological research, while at the same time increasing expectations. In this paper, a brief summary of genetic history with short explanations of most popular genetic techniques is given.

A novel aspartoacylase (ASPA) gene mutation in Canavan disease.

Canavan disease is a severe autosomal recessive leukodystrophy characterized by macrocephaly, ataxia, severe motor and mental retardation, dysmyelination, and progressive spongial atrophy of the brain. The human aspartoacylase (ASPA) gene, which catalyzes the deacetylation of N-acetyl-L-aspartate, is mutated in Canavan disease. In the presented family sequencing analysis for the aspartoacylase gene was performed on the blood samples of the parents as the affected child had died due to Canavan disease. After the mutation was detected, prenatal diagnosis was also performed and heterozygous Y88X mutation was detected in the fetus. In this report, we present a novel mutation Y88X within the aspartoacylase gene in a consanguineous family with an affected child diagnosed as Canavan disease.

Reasons for adult referrals for genetic counseling at a genetics center in Izmir, Turkey: analysis of 8965 cases over an eleven-year period.

A limited numbers of published studies evaluate the referral reasons for genetic counseling services in the literature. These studies are focused on prenatal genetic counseling services, in particular, prenatal diagnosis. In order to provide the most effective and helpful genetic counseling services, genetics professionals need adequate knowledge about the profile of individuals referred for these services. In addition, physicians need increased awareness of the nature of genetic issues in order to make appropriate referrals. This study was intended to provide a descriptive analysis of the referral reasons of patients that received genetic counseling at a genetics center in Izmir, Turkey during an 11-year period. A total of 8965 records generated between 1998 and 2008 from one genetic center (which consists of The Department of Medical Genetics and Division of Pediatric Genetics) were evaluated retrospectively. Of these, 6,258 involved referrals for prenatal reasons, and 2,707 involved referrals for postnatal reasons. Both prenatal and postnatal records were further classified into more specific categories of referral reasons. The most common reason for genetic counseling among the prenatal patients was advanced maternal age (42.0%), followed by high risk results on prenatal biochemical screening tests such as second trimester double test [(serum concentration of alphafetoprotein (AFP), beta-human chorionic gonadotropin (beta-HCG)], triple test (serum concentration of AFP, beta-HCG, oestriol) and integrated test (26.5%). The most common indications for postnatal patients were recurrent miscarriages (28.2%) and infertility (19.7%). A significant increase in number of specific categories of referrals for genetic counseling was observed for the last 3 years after the establishment of the Medical Genetics Department. These data provide useful information about the frequency of referrals to the genetics department, and the feasibility of genetic services. Organization of genetic services and systematic procedures for genetic counseling and genetic testing may improve the public's awareness of genetics and ensure a high standard of patient care.

A severe alpha thalassemia case compound heterozygous for Hb Adana in alpha1 gene and 20.5 kb double gene deletion.

We report a 6-year-old boy diagnosed as transfusion dependent chronic nonspherocytic hemolytic anemia since 40 days old. Hemoglobin H inclusions were detected with brilliant cresyl blue preparation. His parents were found to be normal on physical examination. His mother had hemoglobin level of 9.34 g/dL, accompanied by typical thalassemic changes of the red cells, and inclusion bodies were also detected with brilliant cresyl blue staining. His father had normal hemoglobin level and borderline red cell indices. Mutation analysis using strip assay capable of detecting 22 mutations within the alpha genes was performed for the proband and the parents which revealed that the case was compound heterozygous for Hb Adana in alpha1 gene and 20.5 kb double gene deletion. The father was found to be heterozygous for Hb Adana alpha1 gene whereas the mother was found to be compound heterozygous for 20.5 kb double gene deletion and 3.7 kb single gene deletion. It is well known that non deletional forms of HbH disease are more severe than the deletional forms. This case represents another example of the nondeletional mutation underlying Hb Adana, which is rarely seen in alpha1 gene, and illustrates the distinctive phenotypes of both the deletional and nondeletional forms of hemoglobin H disease within the same family.