Identification of unknown mutations has remained laborious, expensive, and only viable for studies of selected cases. Population-based "reference ranges" of rarer sequence diversity are not available. However, the research and diagnostic interpretation of sequence variants depends on such information. Additionally, this is the only way to determine prevalence of severe, moderate, and silent mutations and is also relevant to the development of screening programs. We previously described a system, meltMADGE, suitable for mutation scanning at the population level. Here we describe its application to a population-based study of MC4R (melanocortin 4 receptor) mutations, which are associated with obesity. We developed nine assays representing MC4R and examined a population sample of 1,100 subjects. Two "paucimorphisms" were identified (c.307G>A/p.Val103Ile in 27 subjects and c.-178A>C in 22 subjects). Neither exhibited any anthropometric effects, whereas there would have been >90% power to detect a body mass index (BMI) effect of 0.5 kg/m(2) at P=0.01. Two "private" variants were also identified. c.335C>T/p.Thr112Met has been previously described and appears to be silent. A novel variant, c.260C>A/p.Ala87Asp, was observed in a subject with a BMI of 31.5 kg/m(2) (i.e., clinically obese) but not on direct assay of a further 3,525 subjects. This mutation was predicted to be deleterious and analysis using a cyclic AMP (cAMP) responsive luciferase reporter assay showed substantial loss of function of the mutant receptor. This population-based mutation scan of MC4R suggests that there is no severe MC4R mutation with high prevalence in the United Kingdom, but that obesity-causing MC4R mutation at 1 in 1,100 might represent one of the commonest autosomal dominant disorders in man.

Nanodiagnostics is the term used for the application of nanobiotechnology in molecular diagnosis, which is important for developing personalized cancer therapy. It is usually based on pharmacogenetics, pharmacogenomics, and pharmacoproteomic information but also takes into consideration environmental factors that influence response to therapy. Nanotechnology in medicine involves applications of nanoparticles currently under development, as well as longer range research that involves the use of manufactured nano-robots to make repairs at the cellular level. Nanodiagnostic technologies are also being used to refine the discovery of biomarkers, as nanoparticles offer advantages of high volume/surface ratio and multifunctionality. Biomarkers are important basic components of personalized medicine and are applicable to the management of cancer as well. The field of nano diagnostics raises certain ethical concerns related with the testing of blood. With advances in diagnostic technologies, doctors will be able to give patients complete health checks quickly and routinely. If any medication is required this will be tailored specifically to the individual based on their genetic makeup, thus preventing unwanted side-effects.

Primary ciliary dyskinesia (PCD) is an autosomal-recessive disorder characterized by impaired ciliary function that leads to subsequent clinical phenotypes such as chronic sinopulmonary disease. PCD is also a genetically heterogeneous disorder with many single gene mutations leading to similar clinical phenotypes. Here, we present a novel PCD causal gene, coiled-coil domain containing 151 (CCDC151), which has been shown to be essential in motile cilia of many animals and other vertebrates but its effects in humans was not observed until currently. We observed a novel nonsense mutation in a homozygous state in the CCDC151 gene (NM_145045.4:c.925G>T:p.[E309*]) in a clinically diagnosed PCD patient from a consanguineous family of Arabic ancestry. The variant was absent in 238 randomly selected individuals indicating that the variant is rare and likely not to be a founder mutation. Our finding also shows that given prior knowledge from model organisms, even a single whole-exome sequence can be sufficient to discover a novel causal gene.

Pregnant women with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) share a common pathophysiology associated with similar risk factors. Genetic variants used to determine the risk of developing T2DM might also be associated with the prevalence of GDM. The aim of the present study was to scrutinize the relationship between the G972R polymorphism of the insulin receptor substrate-1 (IRS-1) gene with GDM in the Saudi female population. This is a case-control study that monitored 500 Saudi women. Subjects with GDM (n = 200) were compared with non-GDM (n = 300) controls. We opted to evaluate rs1801278 polymorphism in the IRS1 gene, which plays a critical role in the insulin-signaling pathway. Genotyping was performed with the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. The frequency of the rs1801278 polymorphism was significantly higher in women with GDM than in women with non-GDM (for TT + CT versus CC: P = 0.02). Additionally, there was a significant increase in the frequency of the Arg-encoding mutant allele from GDM to non-GDM (for T versus C: P = 0.01). Our results suggest that the rs1801278 polymorphism in the IRS-1 gene is involved in the occurrence of GDM in the Saudi population.