Key Genetic Syndromes for Pediatric OSCE Stations: Rapid Revision Guide

This is a comprehensive guide focusing on genetic syndromes frequently encountered in pediatric Objective Structured Clinical Examination (OSCE) Stations.

This curated list is designed to streamline your revision, providing key information such as defective genes, chromosomes, inheritance patterns, and clinical manifestations.

Why Focus on commonly asked syndromes?

In DNB and MRCPCH exams, time-efficient preparation is paramount. Also, repetitions are very common in these exams. The post serves that purpose and can enhance your readiness for OSCE and Multiple Choice Questions (MCQs), Don't hesitate to correct or contribute more using upload feature.

What's Inside

  • Defective Genes: Understand the genetic basis with insights into the defective genes associated with each syndrome.
  • Chromosomes: Explore the chromosomal intricacies, crucial for a comprehensive grasp of the syndromes.
  • Inheritance Patterns: Learn the patterns that govern the transmission of various syndromes.
  • Clinical Manifestations:Insights into the clinical features, aiding in recognition and diagnosis.
Angelman Syndrome Defective Gene: UBE3A (Ubiquitin Protein Ligase E3A)
Chromosomes: 15
Inheritance: commonly a deletion on the maternal chromosome 15; rarely mutations in UBE3A gene.
Microcephaly, Strabismus, Prominent mandible, Ataxic movements, happy demeanor with frequent laughter Intellectual disability, Developmental disability, Seizures, Speech impairment, Atypically happy, Frequent laughter,
Alpha 1-antitrypsin deficiency Defective Gene: SERPINA1 (Serpin Family A Member 1)
Chromosomes: 14
Inheritance: Autosomal recessive
Lunge disease -Emphysema, Liver disease-Cirrhosis, Skin-Panniculitis, Polyangiitis
Achondroplasia Defective Gene: FGFR3 (Fibroblast Growth Factor Receptor 3)
Chromosomes: 4
Inheritance: Autosomal dominant (Most cases occur sporadically)
Short stature with disproportionately short arms and legs, Large head, frontal bossing, flat nasal bridge, Varus, Valgus defects Disproportionate dwarfism, Recurrent ear infection, Hydrocephalus,
Apert Syndrome Defective Gene: FGFR2 (Fibroblast Growth Factor Receptor 2)
Chromosomes: 10
Inheritance: Autosomal dominant (Most cases occur sporadically)
Short thumb with typical radial deviation, symbrachyphalangism, Syndactyly, high-arched palate, Narrow palate, craniosynostosis, midface dissability Intellectual disability

Name Genotype Phenotype Issues
Beckwith–Wiedemann syndrome Defective Gene: Multiple genes, most common CDKN1C and IGF2
Chromosomes: 11
Inheritance: Most are sporadic, some are autosomal dominant
Hemihyperplasia, Macrosomia, Macroglossia Macrosomia, Omphalocele, Increased risk of embryonal tumors - Wilms tumor, hepatoblastoma, neuroblastoma, rhabdomyosarcoma
Bartter syndrome Defective Gene: Mutations in genes related to ion transport in the renal tubules eg SLC12A1, SLC12A2, CLCNKB, and BSND
Chromosomes: Various
Inheritance: Autosomal recessive
Growth failure Hypokalemia, Hypomagnessium, Normal/low blood pressure, Renal salt wasting leading to hypokalemic hypochloremic alkalosis, Polyuria and polydipsia, Hypercalciuria and nephrocalcinosis.
Bloom syndrome Defective Gene: BLM (Bloom Syndrome RecQ like helicase)
Chromosomes: 15
Inheritance: Autosomal recessive
Short stature, Proportional dwarf, long and narrow face, telangiectatic, Immunodeficiency, Mental retardation, Elevated rate of mutation increases chances of malignancies

Name Genotype Phenotype Issues
Charcot–Marie–Tooth disease PMP22 Chr 17 Wasting of lower leg muscle looking like an inverted champagne bottle foot drop, pes cavus, pes planus, Retardation growth.
CHARGE syndrome CHD7 gene Coloboma, Heart malformations, Atresia of the choanae, Genital or urinary malformations, Ear anomalies (lop ears), Photophobia, Photosensitivity, Frequent infections, Neuropathy
Chediak–Higashi syndrome lysosomal trafficking regulator (LYST) gene, AR Hypopigmented hair, skin, eyes Recurrent gingivitis, periodontitis
Cri du chat Del Chr 5 Microcephaly, Microganthism, Hypertelorism, low-set ears, short fingers, single palmar crease Cry that sounds similar to a cat, LBW, Hypotonia, Difficult swallow, Severe speech issues, ASD, VSD, PDA
Crouzon syndrome FGFR2, FGFR3 AD Craniosynostosis: turricephaly, trigonocephaly- fusion of the metopic suture, brachycephaly- fusion of the coronal suture, dolichocephaly- fusion of the sagittal suture, plagiocephaly- unilateral premature closure of lambdoid and coronal sutures, oxycephaly- fusion of coronal and lambdoidal sutures, frontal bossing, hypertelorism Exophthalmos, hydrocephalus. Sensorineural hearing loss, Airway issues,

Name Genotype Phenotype Issues
Dent Disease X-linked recessive, Chromosome Xp11.22, gene CLCN5 codes kidney-specific voltage-gated chloride channel Tubular proteinuria, calciurea, Aminiacudrea, Kaliurea Fanconi syndrome, Nephrocalcinosis, Nephrolithiasis, CKD.
Denys–Drash syndrome Mutations - Wilms tumor suppressor gene, WT1. Classic triad of pseudohermaphroditism, mesangial renal sclerosis, and Wilms' tumor. Growth retardation, Abnormal skeletal development, Nephropathy, and Wilms' tumor. Early nephrotic syndrome
De Grouchy syndrome now Distal 18q- syndrome Deletion of Chr 18 Rocker-bottom feet, Cleft lip and palate, horseshoe kidney, hydronephrosis, polycystic kidney, cryptorchidism, and hypospadias, midfacial hypoplasia Hypotonia, seizures, CNS Dysmyelination, Hypoplasia of the corpus callosum, low IgA levels
Down Syndrome Chromosome 21 has 3 copies, Robertsonian translocation (2 to 4%) Flat head, large tongue, flat nasal bridge, epicanthic fold, slanting eyes, short hand and neck, Bushfield spots in eye, abnormal dentition, single transverse palmar crease, sandal gap deformity Low IQ, Stunted growth, umbilical hernia (90%), Hypotonia, congenital heart disease (ASD, VSD), strabismus, undescended testes, hyper flexible ligaments, epilepsy, Increased risk of ALL, AML, Hypothyroidism, lower rates of fertility
DiGeorge syndrome, Velocardiofacial or 22q11.2 Deletion Syndrome Defective Gene: Microdeletion on chromosome 22q11.2
Chromosomes: 22
Inheritance: Usually sporadic; uncommonly autosomal dominant
Cleft palate, Abnormal facies, velopharyngeal insufficiency Cardiac abnormality (Interrupted aortic arch, truncus arteriosus, and tetralogy of Fallot), Thymic aplasia, Cleft palate, Hypocalcemia/hypoparathyroidism, Learning disabilities, Recurrent infections, Neonatal seizure due to hypocalcemia, hypothyroidism, increased risk of schizophrenia
Duchenne muscular dystrophy Dystrophin gene at locus Xp21. Short arm of the X chromosome, X linked recessive Progressive muscle weakness, first seen in, voluntary muscles followed by involuntary muscles. Pseudohypertrophy of calf, Regression of motor skills, Dilated cardiomyopathy, Gowers sign, contractures, ADHD, Dyslexia
Dravet Syndrome Defective Gene: SCN1A gene (Sodium voltage-gated channel alpha subunit 1), Chromosomes: 2, Inheritance Pattern: Most cases are de novo mutations (sporadic); autosomal dominant in rare familial cases Onset of seizures in the first year of life, often triggered by fever. Multiple seizure types, including generalized tonic-clonic seizures and myoclonic seizures. Developmental delays and cognitive impairment. Behavioral and motor issues. Increased risk of sudden unexpected death in epilepsy (SUDEP).

Name Genotype Phenotype Issues
Edwards Syndrome Chromosome 18 Trisomy, 2nd Most common trisomy, 80% female, 95% spontaneous abortions Microcephaly, LBW, smallmouth, chin, Low set and malformed ears, short sternum,rocker-bottom feet, flexed and overlapping fingers Low survival rate, Malformation of heart, kidney, developmental delay
Ehlers–Danlos syndrome Autosomal Dominant, mutation of collagen encoding and related genes (COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, TNXB, ADAMTS2 etc) Gorlin's sign - Can easily touch tongue to the nose, large eyes, an undersized chin, sunken cheeks, a thin nose and lips (vascular variant), club foot, tendon and/or muscle rupture, acrogeria (premature aging of the skin of extremities Joints -hypermobility, SKin -Stretchy, velvety soft, hyperelastic, easy scaring, CVS - thoracic outlet syndrome, POTS, Raynaud's phenomenon, Other - Hiatus hernia, GER, spontaneous pneumothorax, Arnold Chiari malformation,
Emery Dreifuss muscular dystrophy Mutations in the EMD, LMNA, and other genes. X linked recessive (commonest), AD, AR (rare) 3rd most common form of muscular dystrophy, Triad of muscle weakness, joint contracture, and cardiomyopathy Muscle - weakness in muscles of the arms, legs, face, neck, spine, and heart, cardiac - bradycardia, tachycardia, arrhythmias, heart block.
Epidermolysis bullosa AD, AR, 3 types epidermolysis bullosa simplex (EBS - most common), dystrophic epidermolysis bullosa (DEB), junctional epidermolysis bullosa (JEB) lack of protein keeping dermis and epidermis together and prevent them from moving independently skin which blisters, blisters in the oral cavity, blisters on the hands and feet, scarred skin, thick skin, and nail

Name Genotype Phenotype Issues
Fanconi Anaemia AR, occasionally XLR. 21 FA genes involved in DNA repair identified so far. Microphthalmia and microcephaly are frequently associated Hematological abnormality - macrocytosis or megaloblastic anemia, pancytopenia,(Remember ! Diamond–Blackfan anemia affects - erythrocytes, Shwachman–Diamond syndrome affects - neutrophils) Myelodysplastic syndromes, and acute myeloid leukemia, infertility in males
Fabry disease X linked lysosomal storage diseases causing deficiency of Alpha galactosidase Angiokeratoma, Cornea verticillata or vortex keratopathy - whorl-like cornea Heart - restrictive cardiomyopathy, heart blocks. Skin -Painless Angiokeratomas. Eyes - vortex keratopathy. Kidney -chronic kidney disease due to proteinuria. Neurological - neuropathy, burning extremities, elevated pain sensations
Familial adenomatous polyposis AD, APC gene Adenomatous polyps in the large intestine, Bleeding PR, anemia, Malignant transformation of polyps

G6PD Deficiency Defective Gene: G6PD gene, Chromosomes: X, Inheritance: X-linked recessive Spleenomegaly Hemolytic anemia triggered by oxidative stress (e.g., infections, medications, fava bean ingestion), Jaundice. hemoglobinuria
Galactosemia Defective Gene: GALT gene (Galactose-1-phosphate uridylyltransferase), Chromosomes: 9, Inheritance: Autosomal recessive Jaundice, Hepatomegaly, Cataracts Failure to thrive in infancy, Vomiting, diarrhea,
Glutaric Aciduria Defective Gene: GCDH gene (Glutaryl-CoA dehydrogenase), Chromosomes: 19, Inheritance:Autosomal recessive Macrocephaly, Hepatomegaly Developmental delays, Movement disorders (dystonia, choreoathetosis)
Gouchers disease, See Homocysteinurea
Gorlins Syndrome Defective Gene: PTCH1 gene, Chromosomes: 9, Autosomal dominant Macrocephaly with a prominent forehead; skeletal abnormalities involving the spine, ribs, or skul Multiple basal cell carcinomas, jaw cysts, skeletal abnormalities.

Hemophilia A Chromosomes: X-linked recessive, Defective Gene: F8 gene (Factor VIII gene), Inheritance Pattern: X-linked recessive Prolonged bleeding after injuries or surgeries, Spontaneous joint and muscle bleeding. Easy bruising, Hemarthrosis progressivley leading to pain and joint damage.
Hemophilia B (Christmas Disease) Chromosomes X, Defective Gene: F9 gene, Inheritance Pattern X-linked recessive Bleeding disorders, joint and muscle bleeding.
Huntington's Disease Defective Gene: HTT gene, Chromosomes: 4, Inheritance Pattern: Autosomal dominant Progressive motor dysfunction, including chorea (involuntary, irregular, and jerky movements). Cognitive decline leading to dementia.Psychiatric symptoms, including mood disturbances and behavioral changes. Impaired coordination and balance.
Hemochromatosis Defective Gene: HFE gene, other genes such as HJV, HAMP, and TFR2. Chromosomes: 6, Inheritance: Autosomal recessive; autosomal dominant Skin pigmentation (bronze or gray) Excessive iron absorption leading to iron overload in organs. Fatigue, weakness. Joint pain. Liver cirrhosis.
Hurler Syndrome (MPS I-H) Defective Gene: IDUA gene (produces alpha-L-iduronidase), Chromosomes: 4, Inheritance Pattern: Autosomal recessive Characteristic coarse facial features, skeletal abnormalities, organomegaly. symptoms shortly after birth and progress rapidly, developmental delay, cognitive decline, joint stiffness and contractures, short stature, and cardiac and hepatic disease. Usually die within the first year of life. Read more about Hurler syndrome
Hunter Syndrome (Mucopolysaccharidosis II) Defective Gene: IDS gene (Iduronate-2-sulfatase gene), Chromosomes: X (X-linked recessive), Inheritance Pattern: X-linked recessive Coarse facial features. Enlarged tongue and lips. Organomegaly (liver and spleen). Joint and skeletal deformities, Sever disease in 60% affected, Normal development until 3 or 4 years of age then develops behavioral changes, attention difficulties, speech delay, cognitive decline, and poor performance in school. May present as hydrocephalus.Hearing loss due to deformities in the middle ear, inner ear, and frequent ear infections. Epilepsy. Read more about hunter syndrome.
Hirschsprung's Disease Defective Gene: RET gene, Chromosomes: 10, Inheritance Pattern: Multifactorial, complex genetic and environmental factors Constipation, bowel obstruction, abdominal distension.
Holoprosencephaly Defective Gene: SHH gene (Sonic Hedgehog), Chromosomes: Various (chromosomal abnormalities), Inheritance Pattern: Autosomal dominant or sporadic Microcephaly, midface hypoplasia, Hypotelorism, colobomas and other Facial abnormalities, intellectual disability, hypotonea, dystonea, epilepsy.

Incontinentia Pigmenti (Bloch-Sulzberger Syndrome) Defective Gene: IKBKG gene (Inhibitor of Nuclear Factor Kappa-B Kinase Subunit Gamma)
Chromosomes: X (X-linked dominant)
Usually sporadic; lethal in males
Skin manifestations evolving through stages such as vesicular, verrucous, hyperpigmented, and atrophic. Dental abnormalities. CNS and ocular abnormalities. Limb abnormalities.
Isolated Growth Hormone Deficiency (IGHD) Defective Gene: Multiple genes may be involved (e.g., GH1)
Chromosomes: Various
Inheritance: Autosomal recessive or autosomal dominant
Proportionate Short stature Delayed growth and development
Ichthyosis Defective Gene: Multiple genes depending on type of ichthyosis(TGM1, ABCA12, FLG)
Chromosomes: Various
Inheritance: Autosomal recessive or autosomal dominant
Scaly, dry, or thickened skin. Variable severity, ranging from mild to severe. Redness and inflammation. Palmoplantar keratoderma. Symptoms can range from mild to severe depenidng on variety.Most common type is Ichthyosis vulgaris which is usually mild. Blisters can break into wounds,Hair loss, infections, loss of mobility of joints.

Jacobsen syndrome 11q terminal deletion, Inheritance Pattern: Most cases are sporadic (result from de novo deletions) Developmental delays and intellectual disabilities. Facial dysmorphism (low-set ears, wide-set eyes). Thrombocytopenia (low platelet count), Feeding difficulties, Cardiac abnormalities.
Joubert syndrome Defective Gene: Mutations in several genes, including AHI1, NPHP1, CEP290, TMEM67, and others. Chromosomes: Various Inheritance Pattern: Most cases are autosomal recessive; some may be X-linked recessive or autosomal dominant. Cerebellar vermis hypoplasia. Characteristic molar tooth sign on brain imaging. Ataxia and developmental delays. Ocular motor apraxia. Respiratory abnormalities.

Krabbe Disease Defective Gene: GALC gene (Galactocerebrosidase), Chromosomes: 14, Inheritance Pattern: Autosomal recessive Progressive neurodegeneration, Hypotonia (weak muscle tone), Seizures, Optic atrophy and blindness, Developmental regression, Peripheral neuropathy Additional Information: Krabbe Disease, also known as globoid cell leukodystrophy, is a rare and often fatal genetic disorder. Mutations in the GALC gene lead to a deficiency of the enzyme galactocerebrosidase, resulting in the accumulation of toxic substances in the nervous system. There are early infantile, late infantile, juvenile, and adult-onset forms of Krabbe Disease, with varying onset and severity. Diagnosis involves genetic testing and assessment of enzyme activity. Currently, there is no cure for Krabbe Disease, and treatment is primarily supportive, focusing on symptom management and quality of life.

Lesch Nyhan Syndrome Defective Gene: HPRT1 gene (Hypoxanthine-guanine phosphoribosyltransferase 1), Chromosomes: X (X-linked recessive), Inheritance Pattern: X-linked recessive Severe neurological and behavioral abnormalities, Intellectual disability, Self-mutilation behaviors, including biting of lips and fingers, Gout due to excessive uric acid production. Movement disorders. Lesch-Nyhan Syndrome is a rare X-linked recessive disorder affecting purine metabolism. Mutations in the HPRT1 gene result in a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase. Diagnosis involves genetic testing and assessment of enzyme activity. Management focuses on supportive care, including behavioral interventions and medications to control uric acid levels.
Limb-Girdle Muscular Dystrophy (LGMD) Defective Gene: Multiple genes associated with muscle structure and function (varies depending on the subtype) Chromosomes: Various. Inheritance Pattern: Autosomal recessive or autosomal dominant (depends on the subtype) Progressive weakness and atrophy of pelvic and shoulder girdle muscles. Difficulty with walking and climbing stairs. Variable age of onset and rate of progression. Elevated creatine kinase levels.

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