# Genetic, Paediatric and Nutritional Disorders for NEET PG Pathology: Down, Turner, Klinefelter, Storage Diseases, PEU, Vitamins

Source: https://tracknation.in/story/genetic-paediatric-and-nutritional-disorders-for-neet-pg-pathology-down-turner-klinefelter-storage-diseases-peu-vitamins (TrackNation — free UPSC notes with PYQs)

> NEET PG Pathology: trisomies 21, 18 and 13, Turner and Klinefelter syndromes, fragile X repeats, Wilms tumour, Gaucher, Niemann-Pick and Tay-Sachs, glycogen storage diseases, phenylketonuria, marasmus vs kwashiorkor, vitamin A, D, B1 and B3 deficiency and metabolic syndrome, with a diagram, hooks, vignette MCQs and cards.

## Start Here

🎯 **Exam priority: Moderate.** *Expect: a dysmorphology vignette (Down, Edwards, Patau, Turner, Klinefelter), the
enzyme behind a storage disease, the cherry-red spot, fragile X repeats, the classic Wilms presentation, marasmus vs kwashiorkor and the
vitamin behind a deficiency picture.*

CBME mapping: **PA 11.1–11.3, 12.1–12.3**. Retinoblastoma and neuroblastoma genetics are in article 4.

*Chromosomal disorders, storage diseases and nutritional deficiencies. Drawn by TrackNation.*

## Chromosomal and Gene Disorders

- **Down syndrome**: about 95% from nondisjunction (extra, usually maternal, chromosome 21); about 4% from translocation. Risk
rises with maternal age (about 1/1476 at 20, 1/352 at 35, 1/85 at 40). Heart disease (VSD, atrioventricular septal defect), duodenal atresia,
Hirschsprung disease, coeliac disease, hypothyroidism, leukaemias (ALL, acute megakaryoblastic), atlantoaxial instability and early Alzheimer disease.

- **Edwards (trisomy 18)**: clenched fist with the index finger over the third and fourth, rocker-bottom feet.
**Patau (trisomy 13)**: midline defects — holoprosencephaly, cleft lip and palate.

- **Turner (45,X)**: short stature, ovarian dysgenesis with high gonadotropins and infertility, neonatal lymphoedema, webbed neck,
coarctation and bicuspid aortic valve.

- **Klinefelter (47,XXY)**: the commonest sex-chromosome disorder — tall, small testes, infertility, high gonadotropins; about
30% get gynaecomastia.

- **Fragile X**: unstable CGG repeat in *FMR1* (normal < 54, premutation 55–200, full > 200) — the commonest
inherited cause of intellectual disability and autism.

- **Childhood tumours**: Wilms tumour presents as a painless abdominal mass; WT1 deletion; WAGR = Wilms, aniridia, genitourinary
anomalies. Retinoblastoma presents with leukocoria.

## Storage and Metabolic Diseases

- **Gaucher**: glucocerebrosidase deficiency → glucocerebroside in macrophages (Gaucher cells) → hepatosplenomegaly or CNS
disease; treated with enzyme replacement. **Niemann-Pick**: sphingomyelinase deficiency → sphingomyelin in reticuloendothelial cells.
**Tay-Sachs**: hexosaminidase deficiency → neurodegeneration, cherry-red macular spot, death by about 5; autosomal recessive, carriers
1 in 27 Ashkenazi Jews.

- Mucopolysaccharidoses (e.g. Hurler) are autosomal recessive except MPS II.

- **Glycogen storage**: von Gierke (GSD I) — severe hypoglycaemia, lactic acidosis, hepatomegaly before age 1; Pompe (GSD II);
McArdle (GSD V, muscle phosphorylase) — exercise cramps and rhabdomyolysis.

- **Phenylketonuria**: phenylalanine hydroxylase deficiency → intellectual disability, mousy odour, lighter skin and hair;
lifelong low-phenylalanine diet.

## Nutritional Disease

- **Marasmus** (dry form): severe lack of calories and protein in infants — fat and muscle wasting. **Kwashiorkor**
(wet, oedematous form): older children, often after early weaning when a sibling is born.

- **Vitamin A**: early night blindness, Bitot spots, xerophthalmia. **Vitamin D**: rickets (children) and
osteomalacia; low calcium drives secondary hyperparathyroidism. **Thiamine (B1)**: beriberi — dry (symmetric stocking-glove neuropathy)
and heart failure; Wernicke-Korsakoff in alcohol use. **Niacin (B3)**: pellagra — symmetric photosensitive rash, glossitis, diarrhoea,
mental change. Vitamin C: scurvy (article 2).

- **Metabolic syndrome**: large waist (abdominal fat), hypertension, abnormal fasting glucose or insulin resistance, and
dyslipidaemia.

## Traps the Examiner Sets

- Most Down syndrome = nondisjunction; translocation in about 4%.

- Turner: coarctation and bicuspid valve; Klinefelter: gynaecomastia and small testes.

- Cherry-red spot = Tay-Sachs (hexosaminidase A).

- Gaucher = glucocerebrosidase; Niemann-Pick = sphingomyelinase.

- Kwashiorkor = oedema, older child; marasmus = wasting, infant.

## Memory Hooks & Shortcuts

*Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.*

- 🧠 **Edwards Elects (18) with a clenched fist; Patau Puts holes in the midline (13)** — trisomy 18 vs 13

- 🧠 **Turner: Two heart Troubles — coarctation, bicuspid** — Turner cardiac

- 🧠 **Klinefelter: Kinda tall, Kinda breasts, tiny testes** — Klinefelter

- 🧠 **Cherry on the Tay** — Tay-Sachs cherry-red spot

- 🧠 **Kwashiorkor = Kwashi-water (oedema)** — kwashiorkor vs marasmus

- 🧠 **Pellagra's 3 Ds: Dermatitis, Diarrhoea, Dementia** — niacin deficiency

## Rapid-Revision Cards

- ~95% nondisjunction (maternal); ~4% translocation.

- 1/1476 at 20; 1/352 at 35; 1/85 at 40.

- VSD/AVSD, duodenal atresia, Hirschsprung, leukaemia, early Alzheimer.

- Clenched overlapping fingers, rocker-bottom feet.

- Holoprosencephaly, cleft lip/palate.

- Short, ovarian dysgenesis, webbed neck, coarctation, bicuspid valve.

- Tall, small testes, infertility, gynaecomastia ~30%.

- FMR1 CGG > 200; commonest inherited ID.

- Painless abdominal mass; WT1; WAGR.

- Glucocerebrosidase; Gaucher cells; hepatosplenomegaly.

- Sphingomyelinase.

- Hexosaminidase; cherry-red spot; AR; death by ~5.

- AR except MPS II.

- G6Pase; hypoglycaemia, lactic acidosis, hepatomegaly.

- Muscle phosphorylase; exercise cramps.

- PAH deficiency; mousy odour; diet.

- Dry wasting infant vs oedematous older child.

- Night blindness, Bitot spots.

- Rickets/osteomalacia; ↑ PTH.

- Beriberi, Wernicke-Korsakoff.

- Pellagra: photosensitive rash, diarrhoea, mental change.

- Waist, BP, glucose, lipids.

## Sources

*Facts in this article were checked against these documents.*

- MSD Manual Professional: Down Syndrome; Trisomy 18; Trisomy 13; Turner Syndrome; Klinefelter Syndrome; Fragile X Syndrome; Wilms Tumor — Merck & Co. (MSD Manuals), reviewed 2024–26 (link)

- MSD Manual Professional: Gaucher; Niemann-Pick; Tay-Sachs; Lysosomal Storage Disorders; Glycogen Storage Diseases; Phenylketonuria — Merck & Co. (MSD Manuals), reviewed 2024–26 (link)

- MSD Manual Professional: Protein-Energy Undernutrition; Vitamin A, D, Thiamine and Niacin Deficiency; Metabolic Syndrome — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

- Competency Based Undergraduate Curriculum, Pathology (PA 11–12) — National Medical Commission, 2024

## Test Yourself: Practice Questions

Thirty-two questions in NEET PG style, most of them clinical vignettes.

## Practice Questions (NEET PG pattern)

*Original questions written in the style of the exam: +4 for a correct answer, −1 for a wrong one. Every answer
was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.*

**Q1.** Most cases of Down syndrome are caused by

- (a) mosaicism

- (b) maternal nondisjunction giving an extra chromosome 21

- (c) a Robertsonian translocation

- (d) a paternal deletion

**Answer: (b)** — About 95% nondisjunction; about 4% translocation.

**Q2.** A couple's first child has Down syndrome due to an unbalanced translocation. What share of Down syndrome cases does this mechanism cause?

- (a) about 95%

- (b) none

- (c) about 4%

- (d) about 50%

**Answer: (c)** — Parental karyotyping matters for translocation cases.

**Q3.** The risk of a Down syndrome birth at maternal age 40, compared with 20, is

- (a) slightly lower

- (b) much higher (about 1/85 vs 1/1476)

- (c) lower

- (d) the same

**Answer: (b)** — About 1/352 at 35.

**Q4.** A newborn with Down syndrome has a congenital obstruction of the upper small bowel. A typical associated anomaly is

- (a) malrotation always

- (b) pyloric stenosis only

- (c) intussusception

- (d) duodenal atresia

**Answer: (d)** — Also Hirschsprung and coeliac disease.

**Q5.** The commonest congenital heart lesions in Down syndrome are

- (a) transposition

- (b) tetralogy only

- (c) coarctation and bicuspid valve

- (d) ventricular and atrioventricular septal defects

**Answer: (d)** — Coarctation and bicuspid valve are Turner lesions.

**Q6.** Adults with Down syndrome have an increased risk of

- (a) multiple sclerosis

- (b) Parkinson disease

- (c) Huntington disease

- (d) early-onset Alzheimer disease

**Answer: (d)** — Also leukaemias and hypothyroidism.

**Q7.** A newborn has a clenched fist with the index finger overlapping the third and fourth fingers and rocker-bottom feet. The karyotype is likely

- (a) 45,X

- (b) trisomy 13 (Patau)

- (c) trisomy 18 (Edwards)

- (d) trisomy 21

**Answer: (c)** — Severe heart disease is common.

**Q8.** A newborn has holoprosencephaly and cleft lip and palate. The likely diagnosis is

- (a) trisomy 18

- (b) trisomy 13 (Patau)

- (c) fragile X

- (d) Turner syndrome

**Answer: (b)** — Midline anomalies.

**Q9.** A short girl has high FSH and LH, had puffy hands and feet at birth and has a webbed neck. The karyotype is

- (a) trisomy 21

- (b) 47,XXY

- (c) 45,X (Turner syndrome)

- (d) 46,XY

**Answer: (c)** — Ovarian dysgenesis with hypergonadotropic hypogonadism.

**Q10.** The cardiac lesions typical of Turner syndrome are

- (a) VSD and AV canal

- (b) coarctation of the aorta and bicuspid aortic valve

- (c) pulmonary stenosis only

- (d) transposition

**Answer: (b)** — Also aortic dilatation.

**Q11.** A tall infertile man has small firm testes, gynaecomastia and high gonadotropins. The karyotype is

- (a) 47,XXY (Klinefelter)

- (b) trisomy 21

- (c) 45,X

- (d) 46,XX male only

**Answer: (a)** — The commonest sex-chromosome disorder; about 30% have gynaecomastia.

**Q12.** The commonest sex-chromosome disorder is

- (a) XYY syndrome

- (b) Turner syndrome

- (c) fragile X

- (d) Klinefelter syndrome

**Answer: (d)** — MSD.

**Q13.** A boy with intellectual disability and autism has more than 200 CGG repeats in FMR1. The diagnosis is

- (a) fragile X syndrome

- (b) Huntington disease

- (c) Down syndrome

- (d) myotonic dystrophy

**Answer: (a)** — Normal < 54; premutation 55–200.

**Q14.** The commonest inherited cause of intellectual disability is

- (a) Down syndrome (usually not inherited)

- (b) PKU

- (c) Tay-Sachs

- (d) fragile X syndrome

**Answer: (d)** — Down syndrome is commoner but mostly sporadic.

**Q15.** A young child has a painless abdominal mass, aniridia and genitourinary anomalies. The syndrome is

- (a) Li-Fraumeni

- (b) WAGR (Wilms tumour with WT1 deletion)

- (c) MEN 2

- (d) neurofibromatosis

**Answer: (b)** — Painless palpable mass is the commonest Wilms finding.

**Q16.** A child has hepatosplenomegaly; marrow shows macrophages laden with glucocerebroside. The enzyme deficient is

- (a) hexosaminidase A

- (b) alpha-L-iduronidase

- (c) glucocerebrosidase (Gaucher disease)

- (d) sphingomyelinase

**Answer: (c)** — Treated with enzyme replacement.

**Q17.** Niemann-Pick disease results from deficiency of

- (a) glucocerebrosidase

- (b) sphingomyelinase

- (c) hexosaminidase

- (d) glucose-6-phosphatase

**Answer: (b)** — Sphingomyelin accumulates in reticuloendothelial cells.

**Q18.** An infant loses milestones after 6 months, develops seizures, and has a cherry-red macular spot. The enzyme deficient is

- (a) hexosaminidase (Tay-Sachs disease)

- (b) glucocerebrosidase

- (c) phenylalanine hydroxylase

- (d) muscle phosphorylase

**Answer: (a)** — Death by about age 5; carriers 1/27 Ashkenazi Jews.

**Q19.** Tay-Sachs disease is inherited as

- (a) autosomal dominant

- (b) autosomal recessive

- (c) X-linked recessive

- (d) mitochondrial

**Answer: (b)** — 25% risk when both parents are carriers.

**Q20.** Which mucopolysaccharidosis is the exception to autosomal recessive inheritance?

- (a) Gaucher

- (b) Tay-Sachs

- (c) MPS I (Hurler)

- (d) MPS II

**Answer: (d)** — MSD.

**Q21.** An infant has severe fasting hypoglycaemia, lactic acidosis and a big liver. The likely glycogen storage disease and enzyme are

- (a) von Gierke (GSD I) — glucose-6-phosphatase

- (b) Pompe — acid alpha-glucosidase

- (c) McArdle — muscle phosphorylase

- (d) Gaucher — glucocerebrosidase

**Answer: (a)** — Onset before age 1.

**Q22.** A young adult gets muscle cramps and dark urine from rhabdomyolysis after exercise. The likely glycogen storage disease is

- (a) Pompe

- (b) von Gierke

- (c) McArdle disease (GSD V, muscle phosphorylase)

- (d) Tay-Sachs

**Answer: (c)** — Onset in adolescence or early adulthood.

**Q23.** An untreated child with intellectual disability, hyperactivity, fair skin and hair and a mousy body odour most likely has

- (a) hypothyroidism

- (b) phenylketonuria (phenylalanine hydroxylase deficiency)

- (c) Tay-Sachs

- (d) Down syndrome

**Answer: (b)** — Treated by lifelong phenylalanine restriction.

**Q24.** An infant has severe loss of subcutaneous fat and muscle without oedema. This is

- (a) obesity

- (b) kwashiorkor

- (c) marasmus (dry form)

- (d) rickets

**Answer: (c)** — Severe lack of calories and protein.

**Q25.** A 2-year-old weaned early when a sibling was born now has generalised oedema. The form of undernutrition is

- (a) marasmus

- (b) kwashiorkor (wet, oedematous form)

- (c) beriberi

- (d) scurvy

**Answer: (b)** — Kwashiorkor children tend to be older than marasmic ones.

**Q26.** A child has difficulty seeing in dim light and keratinised patches on the conjunctiva. The deficient vitamin is

- (a) vitamin B1

- (b) vitamin D

- (c) vitamin A

- (d) vitamin C

**Answer: (c)** — Night blindness is an early sign; Bitot spots.

**Q27.** Vitamin D deficiency lowers calcium, which leads to

- (a) hypercalcaemia

- (b) low PTH

- (c) high phosphate

- (d) secondary hyperparathyroidism (raised PTH)

**Answer: (d)** — Causes rickets in children and osteomalacia in adults.

**Q28.** A man with alcohol use disorder develops Wernicke-Korsakoff syndrome. The deficient vitamin is

- (a) vitamin B12

- (b) vitamin A

- (c) niacin (B3)

- (d) thiamine (B1)

**Answer: (d)** — Wernicke-Korsakoff syndrome; also polyneuropathy and heart failure (beriberi).

**Q29.** Symmetric burning and numbness of the feet in a stocking-glove pattern from thiamine deficiency is called

- (a) scurvy

- (b) dry beriberi

- (c) wet beriberi

- (d) pellagra

**Answer: (b)** — Peripheral neurologic deficit.

**Q30.** A patient has a symmetric photosensitive rash on sun-exposed skin, glossitis, diarrhoea and confusion. The deficiency is

- (a) zinc only

- (b) vitamin C

- (c) niacin (pellagra)

- (d) riboflavin

**Answer: (c)** — Advanced pellagra.

**Q31.** The components of metabolic syndrome are

- (a) obesity alone

- (b) large waist, hypertension, abnormal fasting glucose or insulin resistance, and dyslipidaemia

- (c) hypertension and gout only

- (d) diabetes and anaemia

**Answer: (b)** — Abdominal adipose tissue drives it.

**Q32.** A woman with Turner syndrome had puffy hands and feet at birth. The cause was

- (a) hypothyroidism

- (b) heart failure

- (c) nephrotic syndrome

- (d) lymphoedema

**Answer: (d)** — Also loose skin folds at the neck → webbed neck.

### Active Recall

From memory: give the mechanism, risk with maternal age and associations of Down syndrome; distinguish trisomy 18, 13, Turner and Klinefelter; explain fragile X repeats; name the enzyme in Gaucher, Niemann-Pick, Tay-Sachs, von Gierke, McArdle and PKU; contrast marasmus and kwashiorkor; and match vitamins A, D, B1 and B3 to their deficiency diseases.