Developmental disorders

Introduction to Developmental Disorders

Over the past few decades, extensive research efforts have been aimed at the understanding and treatment of disorders that are diagnosed in the developmental period of life. These disorders can be broadly categorized as neurodevelopmental disorders (NDDs) and are further classified based on the symptom patterns such as attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASD), and specific learning disability (SLD). Besides the symptom patterns, many of the NDDs share common comorbid disorders which increase the complexity of diagnosis and clinical management. However, continuing progress has helped to understand the biology, common genetic variants and neurological underpinnings leading to the risk and development of NDDs. The genetic and phenotypic heterogeneities associated with these disorders have directed the present study to undertake an extensive review of the results being published in various forms of literature.

The aim of the study is to provide a comprehensive report on all the details presented in significant publications regarding the etiology, symptomatology, potential risk factors and comorbid disorders of NDDs.

Causes and Risk Factors of Developmental disorders

Professionals agree on some risk factors. The two strongest predictors are a family history of ASD. If an older child has ASD, a sibling is more likely to be affected than other family members. A low birth weight is another. This is especially significant if the birth weight is below 3 pounds, 5 ounces. The risk appears to increase with the degree of prematurity. There is even greater risk if the baby suffers from neurological illnesses following birth, such as congenital rubella syndrome, seizures, and other brain irregularities. The mother’s exposure to rubella or measles during pregnancy increases the risk. Some researchers also believe the use of thalidomide during pregnancy, consumption of alcohol, exposure to certain chemicals, such as pesticides, or perinatal difficulties – sexual health injury, lack of oxygen, metabolic impairments, and maternal nutritional deficiencies – may be implicit risks.

Genetic Factors

Abnormal development (in effect, a failure to develop) is a common problem of childhood to which increasingly complex, often antenatal and postnatal, genetic and teratogenic causes may be recognized or assigned. The concept of genetic causes, once restricted to discrete inherited diseases, has recently been expanded to cover the broader class of developmental disorders. There are at least four major mechanisms by which genes can result in abnormal development: chromosomal anomalies, single gene mutations, polymorphisms of complex genes, and polygenic inheritance. New techniques of molecular and cytogenetic investigation, including in situ localization of specific gene sequences and analysis of DNA polymorphisms, permit mapping of chromosome gene positions. A high percentage of recognized mental retardation syndromes are associated with structural chromosomal anomalies; mental and growth retardation are also very common findings in constitutional chromosomal anomalies.

Autosomal aneuploidies and gonadal mosaicism underlie a large number of mental and growth retardation syndromes and breaks at very specific chromosomal points result in a much smaller number of recognizable syndromes. Some of the recognized syndromes are important from a genetic point of view and may be encountered in the outpatient clinic or general practice setting. They are: Down’s syndrome or mongolism (trisomy 21), the most common chromosomal anomaly, with chromosome breaks at one identified site; Edward’s syndrome (trisomy 18); Turner’s syndrome (XO) producing ovarian dysgenesis; and Klinefelter’s syndrome (XXY or mosaic), found in males with hypogonadism, eunuchoidism, and gynecomastia. These problems are mentioned briefly to remind readers of the more commonly encountered syndromes. Many other complex chromosome anomalies also exist whose significance may be of importance to geneticist or pediatrician but that will not normally be life-threatening per se. In addition, surrounding the discrete position anomalies, more generalized chromosome banding techniques permit assignment of gene order to chromosomal arms; like genetic maps of human and mouse now show a high degree of correspondence. Useful genetic mapping techniques include the moving in situ hybridization, which allows preparation of genetic maps at 1cM resolution selection in pre-implantation mouse embryos, which exclude the gene from a region of mouse chromosome 7 lying between normal recombination events on opposite sides of the required gene.

Environmental Factors

Several possible environmental risk factors for specific developmental disorders in children have been suggested. The main suspects among these are alcohol use or timing of alcoholic intake during pregnancy, pollutants such as lead and polychlorinated biphenyls (industrial pollutants). Cigarette smoking is also suspect, as is exposure to gasoline fumes and other hydrocarbons.

The recent revelations about toxic substances in communities, such as trace elements of arsenic and mercury, have heightened concern about a child’s environment during a sensitive period in early development. At the same time, many of these environmental causative agents are so deeply linked, through addictive habits or low income, with poor prenatal care and inadequate diet in childhood, that it is difficult to establish independently the relative roles of these environmental risk factors alone in causing developmental disorders. Moreover, many of these possible environmental risk factors are believed cumulatively to affect only a very small proportion of the population, and even if they are confirmed, their population-attributable fractions are expected to be low.

Interventions and Treatment of Developmental disorders

Effective early interventions can have great benefits in alleviating the more severe effects of early impairments, as well as in confirming the child’s development in many areas. Ongoing studies of individuals with a range of early developmental, genetic, and biochemical etiological reasons for their developmental disabilities may provide some insights into the nature of the causal processes, and thus the most effective treatments available for these conditions.

Early Intervention

A broad range of early intervention services has been developed to work with children and families. Those delivered in more informal settings have an even broader base in ideas and programs that have developed in individual centers or communities around the world. These can often provide effective programs with families that live in isolated areas where existing facilities might have a problem providing the necessary services for the child. Current research is adding to general beliefs about the positive effect of any such options, and thus they represent another area of promising new developments in the treatment of developmental disabilities. Popular early intervention options include not only the provision of a range of services directly to children with disabilities, but also the development of parent training courses that allow families of these children to have the same specialist knowledge that they can bring to their ‘normal’ children.

Conclusion

In conclusion, developmental disorders are a significant and complex area within medicine, necessitating specialized understanding and intervention. Ongoing advancements in research and technology are enhancing our ability to diagnose and treat these conditions more effectively. However, challenges persist in addressing the diverse needs of affected individuals and ensuring early intervention and comprehensive support. Continued research and innovation are essential for improving the quality of life for those impacted and achieving better therapeutic outcomes.

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INTERNATIONAL HEALTH AND MEDICINE ORGANIZATION IHMO

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