Pathology
Genetic and Paediatric Diseases
Genetic and paediatric diseases for MBBS and NEET-PG: Down, Turner and Klinefelter syndromes, childhood tumours and storage disorders, mapped to NMC codes PA11.1 to PA11.3.
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Genetic and Paediatric Diseases
Genetic and paediatric diseases for MBBS and NEET-PG: Down, Turner and Klinefelter syndromes, childhood tumours and storage disorders, mapped to NMC codes PA11.1 to PA11.3.
This chapter covers the genetic and developmental disorders that present in infancy and childhood. It includes the common cytogenetic abnormalities, the paediatric tumours and tumour-like conditions, and the storage disorders that arise from inherited enzyme deficiencies.
High-yield: Genetic and Paediatric Diseases
- Down syndrome is trisomy 21 and is the most common chromosomal cause of intellectual disability.
- Down syndrome features include a flat facial profile, epicanthic folds, a single palmar crease and an increased risk of congenital heart disease and leukaemia.
- The risk of Down syndrome rises with advancing maternal age, usually through meiotic non-disjunction.
- Turner syndrome is 45,X and presents with short stature, webbed neck, primary amenorrhoea and streak ovaries.
- Klinefelter syndrome is 47,XXY and presents with tall stature, small firm testes, gynaecomastia and infertility.
- Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13) carry a poor prognosis with multiple malformations.
- Autosomal dominant disorders often involve structural proteins, as in Marfan syndrome and hereditary spherocytosis.
- Autosomal recessive disorders often involve enzyme defects, as in the inborn errors of metabolism.
- Lysosomal storage disorders result from enzyme deficiencies that lead to accumulation of undegraded substrate in cells.
- Gaucher disease is the most common lysosomal storage disorder and shows Gaucher cells with a crumpled tissue-paper cytoplasm.
- Tay-Sachs disease shows a cherry-red spot at the macula and progressive neurodegeneration in infancy.
- Neuroblastoma is the most common extracranial solid tumour of childhood and secretes catecholamines.
- Wilms tumour (nephroblastoma) is the most common primary renal tumour of childhood and presents with an abdominal mass.
- Retinoblastoma follows the two-hit hypothesis of tumour suppressor gene loss and can present with leukocoria.
- Sudden infant death syndrome is the sudden unexplained death of an infant, with prone sleeping a recognised risk factor.
Common chromosomal disorders
- **Down syndrome:** Trisomy 21; flat facies, single palmar crease, heart disease, leukaemia risk.
- **Turner syndrome:** 45,X; short stature, webbed neck, streak ovaries, primary amenorrhoea.
- **Klinefelter syndrome:** 47,XXY; tall, small firm testes, gynaecomastia, infertility.
- **Edwards / Patau:** Trisomy 18 and 13; multiple malformations, poor prognosis.
NMC competencies in this chapter
- **PA11.1:** Pathogenesis and features of common cytogenetic abnormalities and mutations in childhood
- **PA11.2:** Pathogenesis and pathology of tumours and tumour-like conditions of infancy and childhood
- **PA11.3:** Pathogenesis of common storage disorders in infancy and childhood
Frequently Asked Questions
What chromosomal abnormality causes Down syndrome?
Trisomy 21, usually from meiotic non-disjunction, whose risk rises with advancing maternal age.
What is the most common lysosomal storage disorder?
Gaucher disease, caused by glucocerebrosidase deficiency, whose macrophages show a crumpled tissue-paper cytoplasm.
Which is the most common extracranial solid tumour of childhood?
Neuroblastoma, a catecholamine-secreting tumour arising from neural crest cells of the sympathetic chain or adrenal medulla.
How does Turner syndrome present?
With a 45,X karyotype giving short stature, a webbed neck, primary amenorrhoea and streak ovaries.
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