This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Types of Genetic Disorders, Subject name: Pediatrics
Which investigation has been performed here to diagnose Edward syndrome? 
Select and explain. 
A. Karyotype, B. FISH, C. MLPA, D. Microarray
B: FISH
Answer: B: FISH 
Explanation: - Fluorescent in situ hybridization (FISH)- molecular cytogenetic technique that uses fluorescent probes to test for the presence or absence of specific chromosome regions. - Trisomy 18 ( Edwards Syndrome ) ( Mnemonic--ROCKY MOUNTAIN) * Rocker bottom foot * Overlapping fingers * Cardiac defects * Kidney malformations * MicrocephalY * Mental retardation Patau syndrome- Trisomy13 Down syndrome- Trisomy21 Turner's syndrome- monosomy X0