EMQ revision - Chromosomal abnormalities

• 14 year old, Male, Gynaecomastia, Low IQ, Eunuchoid habitus, Gynaecomastia, Testicular atrophy, 47 XXY
• Klinefelter's syndrome
• Seminiferous tubule dysgenesis and loss of Leydig cells
• Underlying defects lead to androgen deficiency and cause testicular atrophy, gynaecomastia, and failure of secondary sexual characteristics
• Androgen replacement as treatment but this cannot restore fertility
• 15 year old, Female, Short stature, Webbed neck, Low hairline, Wide spacing of the nipples with a 'shield-shaped' chest, hearing impairment, 45 XO chromosomal analysis
• Turner's syndrome
• Phenotypically female
• Associated with primary amenorrhoea and coarctation of the aorta
• 2 year old, Male, Known chromosomal disorder, New cardiac murmur, Short stature, Epicanthal folds, Simian palmar creases, Auscultation of his heart reveals a harsh pansystolic murmur at the left sternal edge, Not cyanosed, No signs of cardiac failure
• Down's syndrome
• Trisomy 21
• Commonest of chromosomal disorders
• Atrioventricular endocardial cushion defect causes the cardiac disorders
• Increased risk of ALL, Alzheimer's disease and hypothyroidism
• 47 XX + 21 or 47 XY + 21
• Neonate reviewed on labour ward, Hypotonic, Low-set ears, Micrognathia, 'Rocker bottom' feet, 47 XY +18
• Edward's syndrome
• Occipital prominence
• Cleft lip and palate
• Wide spacing of nipples
• Cryptorchidism
• Major cardiac and renal abnormalities
• Death within 3 months of birth
• If survives, there will be serious mental retardation
• Neonate Special Care Baby Unit (SCBU), low set ears, cleft lip and palate, and six fingers on each hand, 47 XY + 13
• Patau's syndrome
• Same as Edward's syndrome
• Death within 3 months of birth, with severe mental retardation even if they do survive past that
• Cri-du-chat syndrome
• Deletion of chromosome number 5
• Cry that is high pitched and sounds like a cat
• Downward slant to the eyes
• Mental retardation
• Microcephaly
• Micrognathia
• Partial webbing or fusing of fingers or toes
• Double Y syndrome
• Essential normal, with normal fertility and mental health
• No increased aggression
• No increased acne
• Only quicker growth and increased final stature versus predicted
• Fragile X syndrome
• Change of X chromosome (FMR1)
• FMR1 produces a protein that helps brain to develop and grow properly
• More repeats, more likely there is to be a problem
• Most common inherited form of mental retardation in boys
• Both boys and girls affected but since girls have 2 X chromosomes they are less likely to take the full brunt
• Prader-Willi syndrome
• 7 genes on chromosome 15 not expressed on paternal chromosome (maternal normal)
• Low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviours, chronic feeling of hunger leading to life threatening obesity
• Genetic imprinting
• Angelman syndrome
• 7 genes on chromosome 15 not expressed on maternal chromosome (paternal normal)
• Intellectual and developmental disability, sleep disturbance, seizures, jerky movements (especially hand-flapping), frequent laughter or smiling, happy demeanour
• Genetic imprinting
• Triple X syndrome
• Usually nothing, most are normal and many are never diagnosed
• Increased risk of delayed language development, EEG abnormalities, motor-coordination problems, auditory-processing disorders and scoliosis
• Accelerated growth until puberty
• Premature ovarian failure
• Personality and psychological problems