What is Down Syndrome?
Down syndrome is a genetic disorder where an individual has a full or partial extra copy of chromosome 21. This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome. It is the most common genetic chromosomal disorder and cause of learning disabilities in children [1].
Down syndrome varies in severity among individuals, causing lifelong intellectual disability and developmental delays. It's important to note that each person with Down syndrome is unique and may possess these characteristics to different degrees or not at all [2].
Characteristics of Down syndrome
One of Down syndrome's most noticeable physical characteristics is its unique craniofacial features. These include midfacial hypoplasia resulting in a flattened face, ocular hypotelorism, mandibular prognathism, and an upward slanting of the palpebral fissures and epicanthic folds [3]. Another common physical characteristic is brachycephaly, a condition where the head is shorter in length than in width, observed in a majority of individuals with Down syndrome [4].
Regarding cognitive development, individuals with Down syndrome often display a deficit in language abilities that usually exceed impairments in visual-spatial capacities [5]. They consistently show relative weaknesses in expressive language, syntactic/morphosyntactic processing, and verbal working memory [6]. However, they are often reported to have preserved visuospatial abilities [7].
Individuals with Down syndrome are often described as having pleasant, affectionate, and generally passive behaviour [8]. They tend to show a strong interest in social interactions, though how this interest is expressed can vary [9]. At the same time, they may experience higher frustration levels and tend to rely on a limited set of coping strategies [10].
In terms of dental health, individuals with Down syndrome often have dental anomalies such as hypodontia, peg-shaped teeth, and enamel hypocalcification [11]. They also often have occlusal disharmony, including anterior open bite, anterior and posterior crossbite, anterior proclamation, and underdevelopment of the maxilla and the midface [11].
Can people with Down syndrome drive?
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In conclusion, while individuals with Down syndrome can operate simple vehicles in controlled environments, driving a car on public roads may pose significant challenges. However, this does not mean that driving is impossible for them. With proper training, vehicle modifications, and ongoing support, some individuals with Down syndrome may be able to drive safely.
Types of Down Syndrome
Trisomy 21: Down Syndrome, as discussed earlier, is primarily caused by an extra copy of chromosome 21 in every cell of a patient's body. This condition is known as Trisomy 21 and is the most common form of Down Syndrome [12, 13, 14].
Mosaic Down Syndrome: In this case, not all cells have an extra copy of chromosome 21. Some cells have the usual two copies, while others have three. This form of Down Syndrome tends to have fewer symptoms than Trisomy 21 and occurs in about 2 per cent of all Down Syndrome cases [12, 15].
Translocation Down Syndrome: The third type of Down Syndrome is called Translocation Down Syndrome. In this case, children have only an extra part of chromosome 21. There are 46 total chromosomes, but one has an additional piece of chromosome 21 attached. This type of Down Syndrome is less common than Trisomy 21 and Mosaic Down Syndrome [12, 13].
Early diagnosis of Down syndrome
Early diagnosis of Down syndrome is crucial for the child's development and family adjustment. It can be made in the nursery, and immediate diagnosis leading to early child stimulation and counselling of the couple has yielded more favourable results [16].
Prenatal screening tests for Down syndrome are offered as routine testing during pregnancy, usually during the first and second trimesters. These tests measure hormone levels in the blood to detect abnormalities and use an ultrasound to look for irregular fluid buildup in the baby's neck [15, 2].
Diagnostic tests can confirm if your baby has Down syndrome before it's born. The two most common diagnostic tests are chorionic villus sampling and amniocentesis. Both tests take uterine samples to analyze chromosomes [15, 2].
Ultrasound, between 14 and 24 weeks of gestation, can be used for diagnosis based on soft markers like increased nuchal fold thickness, small or no nasal bone, and large ventricles [17].
Non-invasive prenatal diagnostic methods are being studied for the diagnosis of Down syndrome prenatally. These are based on fetal cells in the maternal blood and cell-free fetal DNA in the maternal serum [17].
Quantitative fluorescence polymerase chain reaction (QF-PCR) is a reliable and rapid method for diagnosing DS, providing results within 24 hours [18].
After a baby is born, the provider may make an initial diagnosis of Down syndrome based on the physical signs of the syndrome. The provider can use a karyotype genetic test to confirm the diagnosis. The test can check for extra chromosomes in a sample of the baby's blood [2].