📋 Paediatrics
Genetic Disorders in Paediatrics Complete Guide to Aneuploidies Down Syndrome Turner Syndrome Microdeletion and Imprinting Disorders
Genetic disorders in paediatrics include chromosomal abnormalities, gene mutations, and epigenetic conditions that affect growth, development, and organ function in children. This detailed guide explains major paediatric genetic disorders including aneuploidies such as Down syndrome, Edwards syndrome, and Patau syndrome, as well as Turner syndrome and Noonan syndrome. It also covers microdeletion syndromes like DiGeorge syndrome, genomic imprinting disorders such as Prader Willi syndrome and Angelman syndrome, and trinucleotide repeat disorders including Fragile X syndrome. Learn the causes, genetic mechanisms, clinical features, diagnosis methods, and management approaches for these important childhood genetic conditions in a clear and comprehensive format for students, medical learners, and healthcare professionals.
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Frequently Asked Questions
❓ What are genetic disorders in paediatrics?
Genetic disorders in paediatrics are diseases caused by abnormalities in genes or chromosomes that affect growth, development, metabolism, and organ function in children. They may result from chromosomal abnormalities, gene mutations, microdeletions, genomic imprinting defects, or trinucleotide repeat expansions.
❓ What is aneuploidy in genetic disorders?
Aneuploidy is a chromosomal abnormality where there is an abnormal number of chromosomes due to nondisjunction during meiosis. Examples include trisomy conditions such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and Patau syndrome (Trisomy 13).
❓ What causes Down syndrome?
Down syndrome is caused by an extra copy of chromosome 21. The most common mechanism is meiotic nondisjunction leading to free trisomy 21. Less common causes include Robertsonian translocation and mosaicism.
❓ What are the key clinical features of Down syndrome?
Typical features include hypotonia, intellectual disability, flat facial profile, epicanthal folds, single palmar crease, congenital heart defects such as atrioventricular septal defect, and increased risk of leukemia and thyroid disorders.
❓ What is Edwards syndrome?
Edwards syndrome is caused by trisomy 18 and presents with severe developmental delay, micrognathia, low-set ears, clenched fists with overlapping fingers, rocker-bottom feet, and congenital heart defects.
❓ What is Patau syndrome?
Patau syndrome results from trisomy 13 and is characterized by severe central nervous system malformations, cleft lip and palate, microphthalmia, polydactyly, and congenital heart disease.
❓ What is Turner syndrome?
Turner syndrome is a chromosomal disorder affecting females caused by monosomy X (45,X). It leads to short stature, webbed neck, gonadal dysgenesis, primary amenorrhea, and cardiovascular abnormalities such as coarctation of the aorta.
❓ What is Noonan syndrome?
Noonan syndrome is an autosomal dominant genetic disorder caused by mutations affecting the RAS-MAPK signaling pathway. It presents with short stature, hypertelorism, webbed neck, and congenital heart defects such as pulmonary valve stenosis.
❓ What are microdeletion syndromes?
Microdeletion syndromes occur due to the loss of small chromosomal segments that may not be visible on standard karyotyping. Examples include DiGeorge syndrome (22q11 deletion), Williams syndrome, and Cri-du-chat syndrome.
❓ What is genomic imprinting in genetic disorders?
Genomic imprinting is an epigenetic mechanism where gene expression depends on whether the gene is inherited from the mother or father. Disorders related to imprinting include Prader-Willi syndrome and Angelman syndrome.
❓ What causes Prader-Willi syndrome?
Prader-Willi syndrome occurs due to loss of paternal gene expression on chromosome 15. It presents with hypotonia in infancy, hyperphagia, obesity, intellectual disability, and hypogonadism.
❓ What causes Angelman syndrome?
Angelman syndrome occurs due to loss of maternal gene expression on chromosome 15, particularly involving the UBE3A gene. It is characterized by severe intellectual disability, seizures, ataxia, and frequent laughter.
❓ What are trinucleotide repeat disorders?
Trinucleotide repeat disorders are genetic conditions caused by abnormal expansion of repeated DNA sequences. These disorders often show anticipation, meaning symptoms become more severe in successive generations.
❓ What is Fragile X syndrome?
Fragile X syndrome is the most common inherited cause of intellectual disability. It is caused by CGG trinucleotide repeat expansion in the FMR1 gene and is characterized by intellectual disability, long face, large ears, and macroorchidism.
❓ How are genetic disorders diagnosed in paediatrics?
Diagnosis involves genetic testing such as karyotyping, fluorescence in situ hybridization (FISH), chromosomal microarray analysis, PCR-based tests, and next-generation sequencing. Prenatal diagnosis may involve amniocentesis or chorionic villus sampling.