Chromosomal abnormalities in children are caused by errors inmitosis, maternal age or meiosis (Munne et al., 1995). Meiosisnormally occurs when there is an error in cell division during thedevelopment of the sperm and egg cell. Mitosis is also an error incell division that occurs later after the egg and sperm havedeveloped. Maternal age comes with the age of the mother wherebycomplications arise because the eggs of a woman are as old as themother is. This poses a risk of chromosomal abnormality to the unbornchild. In the United States, it is estimated that out of every 150children born one of them suffers from a chromosomal abnormality.Chromosomal abnormalities cause a range of abnormalities to theunborn child and causes death of the fetus or embryo before the childcan be born in some cases (Lobo & Zhaurova, 2008). This papergives an in-depth analysis of the various aspects of chromosomalabnormalities in children.
Chromosomal abnormalities are diagnosed using a blood test afterbirth or prenatal test before birth (Lobo and Zhaurova, 2008). Thecells are then taken to the laboratory for testing after growth. Thisis done to assess the arrangement of the cell after and to makekaryotype pictures which show shape, number and type of chromosomesthus aiding in the identification of any abnormalities. The mostcommon type of chromosomal abnormality is Down syndrome. It isestimated that out of every 800 newborn babies one of them suffersfrom this syndrome (CDC, 2014). Other chromosomal abnormalitiesinclude trisomy, sex chromosomes abnormalities, Turner syndrome, andKlinefelter syndrome. There are other less common abnormalitiesincluding chromosomal deletion, duplication, inversion,micro-deletion and translocation and ring chromosomes. In seekingtreatment, parents should consult doctors for help. Even though thechances are slim it is paramount for a parent to seek medical help ifa mother is pregnant and has had a baby earlier with a chromosomalabnormality.
Prognosticimportance of structural chromosomal abnormalities in children withhyperdiploid (greater than 50 chromosomes) conditions
Hyperdiploidis a widespread cytogenetic abnormality in childhood B-cell precursorALL (Acute Lymphoblastic Leukemia). Most hyperdiploid ALLcytogenetically traits occur due to a nonrandom X chromosome gain.Many questions remain despite the high frequency of karyotypicsubgroups. These questions are related to etiology, genetic changes,cell origin, epidemiology, high hyperdiploid pathogeneticconsequences and its formation. Several studies have been carried outin the recent past, focusing on some basic important issues abouthyperdiploid chromosomal abnormality (Bareille et al., 1997).Agood example of this is “Prognostic importance of structuralchromosomal abnormalities in children with hyperdiploid (greater than50 chromosomes) acute lymphoblastic leukemia,” Conducted by(National Center for Biotechnology Information, 1989).
According to this study, it is estimated that in every four childrenwho are diagnosed with acute lymphoblastic leukemia (ALL), one ofthem has high hyperdiploid (greater than 50 chromosomes).Unfortunately, most of these children fail to get therapy. The studyinvestigated 138 children, 68 girls and 70 boys with the condition,with the aim of assessing the cytogenetic and initial clinicalfeatures, which might foretell treatment failure. The result of thisstudy was as follows 85 children from both gender that are arepresentative of 62% of the total had structural chromosomalabnormalities laboratory and clinical features of this group were nodifferent from the 53 case of those with numeric abnormalities only.Twenty-Eight individuals did not get better from the treatmentin this study as indicated after a follow-up of four years. Malegender and structural chromosomal abnormalities present wereindependently linked to treatment failure after multivariateanalysis. Thus, in structural chromosomal abnormalities inhyperdiploid (greater than 50 chromosomes) ALL you need not repeatthe whole condition each time gives a different definition ofbiologically different leukemia form, which is characterized by drugresistance likelihood.
Chromosomal abnormalities found among 34910 newborn children:results from 13-year incidence study in Arhus, Denmark: JohannesNielsen and Mogen Wohlert (1991) conducted this study with an aim offinding out how environmental factors affect pregnancy, fetus andbirth. The 13-year-old incidence research on sex chromosomeabnormality showed that at least one out of every 448 newborns had anabnormality in the sex chromosome. Klinefelter syndrome and Turnersyndrome were the most common abnormalities according to the studyfindings. Of the 78 surviving children of the total 34 910 childrenwho had sex chromosome abnormalities none had mental retardation. Thechildren who had reached school age attended the regular schools.
Those with Klinefelter, XYY or XXX and aged 15-19, approximately 77%of this group had at one time received remedial teaching. Moreover,29 were in the process of receiving the remedial teaching.Furthermore, 32% had received special classes at one point due toproblems in learning, 24% of them were continuing with the classeswhen the follow up was conducted. The sample group showed no increasein criminal activity frequency or behavior disorder. In addition tothis, there were no increased physical or mental disorders. Theplanned distribution in terms of training and occupation of the 25youths aged 15-19 with sex chromosome abnormalities was the same asthat of their siblings (Nielsien and Mogen, 1991).Klinefelter boys were administered testosterone undecanoatetreatment, which is a therapeutic drug, from puberty while as theTurner girls from the age of 7 were administered with growth hormonetreatment. Girls with Turners’ syndrome at the age of 12 were givenestrogen doses.
From this study, readers understand that reduction and prevention inmental development deviation from normality for a child with sexchromosomes abnormalities is possible. This can be achieved if aparent is counseled and informed regularly and if social resourcesand education are made available to those in need. This studyaddressed all the four sex chromosomal abnormalities: XXX,Klinefelter syndrome, Turner syndrome and XYY. The study proposesthat the support, information, and support groups should befacilitated to parents with children with these challenges. Inaddition to this, parent needs assistance, counseling depending ontheir child condition, the parent resource in term of finance,socially, psychologically, precise sex chromosome abnormality(Nielsien and Mogen, 1991).
Therapy-related myelodysplastic syndrome and acute myeloidleukemia in children: correlation between chromosomal abnormalitiesand prior therapy. According to scientists, author and year thesetwo conditions are thought to be a result of mutation events causedby radiation therapy, chemotherapy, immunosuppressive therapy orpre-existing conditions. In a study conducted on this topic, theresults showed that most children with therapy related acute myeloidleukemia or myelodysplastic syndrome (MDS) had in one way or theother being exposed to either epipodophyllotoxin and alkylatingagents (Eskenazi et al., 2002).Epipodophylotoxins are anti-cancer drugs derived from a treeto kill tumor cells.
The study was conducted on a sample of 20 children with Acute MyeloidLeukemia (AML) or Myelodysplastic Syndrome (MDS). The age bracket forprimary neoplasm was between six months to sixteen years of age whileas for secondary neoplasm was 1-24. In this group, 12 had chromosomalabnormalities (Eskenazi et al., 2002). Ten of the twelve had been atone time exposed to therapy related to either MDS or AML. MDS and AMLare therapy related clinical syndromes that result from acomplication that comes after cytotoxic therapy (Eskenazi et al.,2002)
Chromosomal abnormalities among children born with conotruncalcardiac defects
Conotruncal heart abnormalities are related to division or faultyconotruncal septation of the solitary primitive heart-tube thisdivision causes two outflow tracts, the two outflow tracts are causedby two swelling fusion that comes from the trunk body. Recently therehas been increasing awareness of chromosomal abnormality andconotruncal association (Lammer et al., 2009). This association isnoted a study conducted in California to describe the relationshipbetween conotruncal heart malformation and chromosomes abnormalities.The results indicated that from a population of 974,579infants/fetuses approximately 622 infant/fetuses were confirmedaortopulmonary septation defect, 5% of the 622 suffered fromchromosomal abnormalities (Lammer et al., 2009).
Distinctive demography, biology and outcome of acute myeloidleukemia and myelodysplastic syndrome in children with Down syndrome:children`s cancer group studies 2861 and 2891.
According to the result of studies carried in the recent past onacute leukemia (AML), for children with Down Syndrome (DS), childrenwith this condition have more megakaryoblastic leukemia andexperiences favorable outcome compared to other children. A groupcalled Children Cancer Group conducted further research on this. Theyinvestigated the biology and demography of children with or withoutDS response in MDS and AML (Lange et al., 1998). The studies assessedthe induction therapy timing and contrasted marrow transplantationwith post remission chemotherapy in 1,206 children. From this number,9.8% had Down syndrome. The patients with Down syndrome were youngwith low platelet and white blood cells.
The results were that the child with Down syndrome were biologicallyand demographically different that of children without the Downsyndrome (Lange et al., 1998).
Short-term memory and vocabulary development in children with Downsyndrome and children with specific language impairment
In a study conducted on this by Hick et al. (2005), a comparisonbetween developments of visuospatial short-term memory and verbaldevelopment and vocabulary was done. The participants included kidswith DS condition, kids with specific impairment in language andnormal developing children participated as a control group. Over aperiod of one year, all participants completed test receptive andexpressive vocabulary tasks, visuospatial short-term memory, andverbal short-term memory. In verbal short-term memory, similaritieswere seen. Children specific language impairment had problems withvisual-spatial short-term memory compared to other groups. The threegroups performed almost the same in visuo-spartial short-term memoryperformance. The clinical groups performed the same in vocabularywhile as the normal developing children performed better than therest in vocabulary.
Sperm aneuploidy in fathers of children with paternally andmaternally inherited Klinefelter syndrome. Eskenazi et al. (2002)conducted this study with the aim of finding out the associationbetween fathering kids with trisomy and aneuploidy sperm frequency.The findings of this study were that children fathered by fatherswith higher XY sperm aneuploidy frequencies had Klinefelter syndrome(Eskenazi et al., 2002). This shows a heritable relationship forKlinfelter’s syndrome. Thus, one whose father had aneuploidy spermfrequency has a higher risk for the syndrome.
Growth curve for girls with Turner syndrome
In study conducted by Lyon, Preece and Grant (1985) to see whetherTurner syndrome causes increase in height in girls with thiscondition. The growth chart was prepared with data obtained fromEuropean patients. Retrospective data was used to evaluate the girl`sheight. Results showed that it was possible to calculate the girl’sheight at adulthood (Bareille et al., 1997). Furthermore, from thisstudy estrogen, which is used to increase the girl’s growth, had noeffect on their height.
This is a rare genetic condition that causes delayed development,impairs the speech severely, causes intellectual disability andmovement problems this is so because it impinges on the nervoussystem. In children, this disease causes epilepsy, microcephaly thatis small head size. Such children are always happy and have a problemsleeping (Dan, 2007). A study conducted in the year 2005 on Angelmansyndrome on a consensus statement, was published in 1995 with the aimof giving a summary of the Angelman syndrome salient clinicalfeature. This was done in order to aid the clinician to make accuratediagnosis, and timely too. The findings showed that a review of theconsensus was needed in order to come up with a method that would beeffective in helping the clinicians to carry out diagnostic test andhave all the support they may need (Dan, 2007). In addition to this,the study suggested that the Angelman syndrome phenotypicalcharacteristics ought to be known in advance before any testing canbe conducted.
In brief, children experience chromosomal abnormalities for differentreasons. The major chromosomal abnormalities in children include DownSyndrome, Turner’s Syndrome, and Klinfelter’s Syndrome. Theseabnormalities may result from the maternal age of mothers wherebymothers who give birth to children in their old age are more likelyto bear abnormal children. The abnormality may also be hereditarywhereby the father’s sperms are aneuploid. This is the case inKlinfelter’s syndrome. These abnormalities can be diagnosed andtreated. For instance, Down syndrome manifests itself through poormemory while Angelman syndrome manifests itself through slowdevelopment.
Bareille P1, Massarano AA, Stanhope R.1997. “Final height outcomein girls with Turner syndrome treated with a combination of low doseestrogen and oxandrolone.” National Center for BiotechnologyInformation, U.S. National Library of Medicine. Internet source
Dan, B. 2007. Angelman syndrome. London: Mac Keith Press.
Eskenazi B, Wyrobek AJ, Kidd SA Lowe X, Moore D, Weisiger K, AylstockM. 2002. Sperm aneuploidy in fathers of children with paternally andmaternally inherited Klinefelter syndrome. Hum Reprod. 17(3):576-583.Doi: 10.1093/humrep/17.3.576.
García Ramírez M1, Csanyi B, Martínez Antón J, Delgado MarquésM, Bauzano Poley E. 2008. Genetic and clinical diagnosis of Angelmansyndrome. Case Reviews. An Pediatr (Barc). 2008 Sep69(3):232-8.
Hick RF1, Botting N, Conti-Ramsden G. 2005. Short-term memory andvocabulary development in children with Down syndrome and childrenwith specific language impairment. Development Medicine & ChildNeurology 47(8):532-538. Doi:10.1111/j.1469-8749.2005.tb011187.x.
Lammer, E. J., Chak, J. S., Iovannisci, D. M., Schultz, K., Osoegawa,K., Yang, W., Carmichael, S. L. and Shaw, G. M.2009. Chromosomalabnormalities among children born with conotronical cardiac defects.Birth Defects Research Part A: Clinical and Molecular Teratology,85: 30–35. doi: 10.1002/bdra.20541.
Lange BJ, Kobrinsky N, Barnard DR, Arthur DC, Buckley JD, Howells WB,Gold S, Sanders J, Neudorf S, Smith FO, Woods WG. Distinctivedemography, biology and outcome of acute myeloid leukemia andmyelodysplastic syndrome in children with Down syndrome: children`scancer group studies 2861 and 2891. Blood. 1998 Jan 1591(2):608-15.
Lobo I, Zhaurova K. 2008. Birth defects: cause and statistics. NatureEducation 1(1):18.
Lyon AJ, Preece MA, Grant DB. 1985. Growth curve for girls withturner syndrome. Arch Dis Child 60:932-935.Doi:10.1136/adc.60.10.932.
Munne S, Alikani M, Tomkin G, Grifo J, Cohen J. 1995. Embryomorphology, development rates and maternal age are correlated withchromosome abnormalities. PMID 64 (2): 382-391.
Nielsen J and Mogen Wohlert. 1991. Chromosome abnormalities foundamoung 34910 newborn children: results from 13-year incidence studyin Arhus, Denmark. Birth defects Orig. Artic. Sex, 209-223.
Williams CA, Angelman H, Clayton-Smith J, Driscoll JE, HendricksonJE. 1995. Angelman Syndrome: consensus for diagnostic criteria. AJ ofMed 56: 237-238.