Muscle, Connective Tissue, and Neonatal Disorders

The skeleton provides the framework and anchor points against which muscles, attached via tendons, can exert force. Three types of cells are involved in making bone: osteoblasts, osteoclasts, and cartilage. The human muscle system is made up of three types of muscle tissue: skeletal, cardiac, and smooth. The neonate period of life is the first 4 weeks after the birth of an infant. This chapter presents 11 genetic disorders that affect muscles, connective tissue, and newborns. These include achondroplasia, Charcot-Marie tooth syndrome, Duchenne Muscular Dystrophy, Ellis-Van Creveld syndrome, amyotrophic lateral sclerosis, Marfan syndrome, fibrodysplasia ossificans progressive, myotonic dystrophy, Angelman syndrome, Prader-Willi syndrome, fragile-X syndrome, and Waardenburg syndrome.

Digestive, Ear/Nose/Throat, and Eye Disorders

The digestive system includes the structures and organs involved in processing of foods required for growth, development, maintenance, and body repair. Most diseases affecting this system are due to infections from bacteria, viruses, protozoa, and fungi, while others are hereditary. The ear, nose, and throat (ENT) system is a complex set of structures sharing slightly interrelated mechanisms of operation. While some disorders of the ENT are hereditary, environmental influences play a big role. Diseases that affect eyesight primarily centre on three layers of the eye (sclera, choroid, and retina) which make eyesight possible. Disorders of metabolism occur when a crucial enzyme is disabled, or if a control mechanism for a metabolic pathway is affected. The chapter focuses on 14 diseases with suspected genetic causes including cystic fibrosis, diabetes, glucose-galactose malabsorption, hemochromatosis, obesity, Wilson's Disease, Zellweger syndrome, deafness, Pendred syndrome, Best Disease, glaucoma, gyrate atrophy, male pattern baldness, and Alport syndrome.

Genetics and Public Health

This chapter wraps up by discussing the crucial role played by public health specialists who must reconcile traditional public health concerns of health inequality and equity with safe and effective health interventions and diagnostics that meet individual health needs. Since most genetic diseases in the realm of public health are an interplay of different genetic, lifestyle, and environmental factors, genomic science has given greater emphasis to the importance of molecular and cellular mechanisms in health and disease. New biological knowledge must be integrated with the social and environmental models to improve health at individual and population levels. Public health specialists must now be able to integrate genome-based knowledge into public health in a responsible, ethical, and effective way and anticipate the increase in the health service requirements likely to occur in the future. The foundational pillars of bioethics (beneficence, non-maleficence, autonomy, and justice) must be protected by all public health stakeholders.

Genes

The advent of recombinant DNA technology has offered new opportunities for innovations to produce a wide range of bioproducts in food and agriculture, health and disease, and environment. Biotechnology is recognized universally as one of the key enabling technologies for the 21st century forming the basis of genetic engineering where genes are isolated, modified, and inserted into organisms. The new CRISPR-Cas9 technology has made it easier to make direct changes to a DNA strand called gene editing. In applied sciences such as clinical medicine, biotechnology, forensics, molecular, and evolutionary biology, sequencing DNA has become an important tool. Gene therapy is a technique used to correct single gene disorders where a cloned normal gene is separated and inserted into a cloning vector. Biotechnology has called for oversight and regulation in ways that makes its application and products safe for human use and operating within human ethical and social guidelines. This chapter explores recombinant DNA technology.

Genes

Two types of nucleic acids, DNA and RNA, carry genetic information of organisms across generations. Many researchers are credited with the early work that laid the foundation of the discovery of the structure of DNA. During cell division, the cell replicates its DNA and organelles during the synthesis (S) phase of the cell cycle. Four main steps are involved in the processes of replication. DNA replication errors and cells have evolved a complex system of fixing most (but not all) of those replication errors proofreading and mismatch repair. With repeated cell division, the DNA molecule shortens with the loss of critical genes, leading to cell death. In gonads, a special enzyme called telomerase lengthens telomeres from its own RNA sequence which serves as a template to synthesize new telomeres. Although most DNA is packaged within the nucleus, mitochondria have a small amount of their own DNA called mitochondrial DNA. This chapter explores this aspect of genes.

Cell Division

Cells divide for three main reasons: growth and development, replace worn-out or injured cells, and reproduction of offspring. Cell division is part of the cell cycle divided into five distinct phases. The diploid state of the cell is the normal chromosomal number in species. During sexual reproduction, the cell's chromosome number is reduced to a haploid state to ensure constancy in chromosome number and thus continuation of the species. The process of cell division is controlled by regulatory proteins. Mitosis occurs in all body cells and is divided into four phases. Meiosis, which occurs in only the germ cells involved in reproduction, divides the chromosomes in two rounds termed meiosis I and meiosis II (reduction division). The human lifecycle starts with gametogenesis, the process that forms gametes which then combine to form a zygote. The zygote quickly becomes an embryo and develops rapidly into a foetus. This chapter explores cell division.

Cancers

With more than half of all cancer cases occurring in less developed nations of the world, cancer is a source of significant and growing mortality worldwide, with an increase to 19.3 million new cancer cases per year projected for 2025. Standard current treatments for cancer include surgery, radiotherapy, and a host of other systemic treatments comprising cytotoxic chemotherapy, hormonal therapy, immunotherapy, and targeted therapies. Referred to as the “guardian of the genome,” the alteration or inactivation of p53 tumour-suppressor gene by mutation or by its interactions with oncogene products or DNA tumour viruses can lead to cancer. The p53 is mutated in about half of almost all types of cancer arising from a wide spectrum of tissues. This chapter focuses on several types of cancer including breast and ovarian, colorectal, small cell lung carcinoma, malignant melanoma, pancreatic, prostate, neurofibromatosis, multiple endocrine neoplasia, and retinoblastoma.

Epigenetics

This chapter focuses on epigenetics: the study of stable, often heritable changes that influence gene expression but are not mediated by DNA sequence. These changes play crucial roles in chromatin state regulation which influences processes such as gene expression, DNA repair, and recombination. Evidence demonstrates that epigenetic patterns are altered by environmental factors which are associated with disease risk including diet, smoking, alcohol intake, environmental toxicants, and stress. Studiers have linked environmental pollutants with epigenetic variations particularly changes in DNA methylation, histone modifications, and microRNAs. Growing data have linked epigenetic alterations with heavy metal exposure, organic toxicants, and water chlorination by-products. Studies focusing on the effects of air pollution in humans demonstrate an association between exposure to air pollution and DNA methylation. Several classes of pesticides can modify epigenetic marks, including endocrine disruptors, persistent organic pollutants, arsenic, several herbicides, and insecticides. This chapter explores epigenetics.

Genes

Genes are regions on DNA that contain the instructions for making specific proteins. In humans, genes vary in size from hundreds of DNA bases to over 3 million base pairs. From DNA to proteins, two steps are involved. Transcription is accessing the gene and reading the instructions therein in the nucleus producing as a single strand of RNA called messenger RNA (mRNA). Translation is reading the instructions on mRNA to assemble the specified proteins on the surface of ribosomes. Genetic mutations are heritable, small-scale alterations in one or more base pairs that damage DNA. Although new mutations introduce new variation, these are constantly removed from populations. Mutations can arise naturally during DNA replication or can be caused by environmental factors like chemicals or radiation. They can be harmful, neutral, or beneficial to the organism and are generally of five types: point mutations, frameshift mutations, transposons, transitions, and transversions. This chapter explores this aspect of genes.

Cellular Basis of Life

To qualify as living, units of life called cells must be identifiable, distinct, and demonstrate most or all the qualities of life. Cells tremendously vary in size from about 0.5-500 micrometers. The smallest known single cells are those of bacteria while most higher organisms have multiple cells differentiated and functioning together as a single system. Communication in cells involves cell signaling, reception, transduction, and response. Signals received at the surface of the cell from other cells, or from blood or tissue fluid must be transferred to various parts of the cell and a cell response initiated. Cells actively take in raw materials which they use to function and perform maintenance activities. Collectively these activities are called cellular metabolism catalysed by enzymes. To avoid chaos in the body, cells maintain control of what reactions are needed all the time, needed only certain times or needed very rarely. This chapter explores the cellular basis of life.