Question

The "cri – du - chat" syndrome is caused by a change in chromosome structure involving
A. Deletion
B. Duplication
C. Inversion
D. Translocation

Answer 1

This is a rare genetic disorder or an unusual condition which is caused by mutation of a chromosome which is responsible for irregular growth of the larynx, low birth weight, or may they may have respiratory difficulties.
Complete answer:
An unusual condition caused by a mutation on the short arm of chromosome $5$ ($1$ in $50,000$live births), Cri du chat is a rare genetic disease due to a defective part of chromosome $5$. It was first described in $1963$ by Lejeune. The name of this syndrome is French for "cry of the cat," referring to the characteristic cry of children with this disease. The cry is caused by irregular growth of the larynx, which after a few weeks of birth becomes normal. Cri du chat infants have low birth weight and may have respiratory difficulties. The size and position of the delete differ between the individuals affected, but findings show that greater deletions appear to produce more extreme effects than lesser deletions.
Hence, the correct answer is an option (A) 'Deletion'.
Additional information: -
-A high-pitched cat-like scream, behavioral retardation, slow growth, distinctive facial features, small head size (microcephaly), broad-spaced pupils (hypertelorism), low birth weight, and poor muscle tone (hypotonia) in childhood are typically the clinical signs of cri du chat syndrome. In time, the cat-like cry usually becomes less noticeable.
-Many people who have Cri du Chat syndrome have communication difficulties. Half of the children learn enough language skills to communicate. Some people learn to use sentences, while others use a few simple words, gestures, or sign language to communicate themselves.
-Other characteristics can include problems with hyperactivity, eating, walking delays, scoliosis, and severe retardation. A limited percentage of children are born with severe organ defects and other life-threatening medical problems, but there is a reasonable life expectancy for most people with Cri du Chat syndrome.
-Both children and adults are generally cooperative and comfortable with this syndrome and enjoy social contact.
-Cri du chat syndrome is usually diagnosed in the hospital at birth. The clinical signs associated with the disorder may be noticed by a healthcare professional. In young infants, the cat-like sound is the most common clinical characteristic and is commonly diagnosed with cry du chat syndrome.
-In addition, a study of the chromosomes of the organism can be done. In chromosome analysis, the missing part (deletion) of the short arm of chromosome five could be seen. If not, to show the deletion, a more detailed form of genetic test called FISH analysis could be required.

Note: For this syndrome, no particular medication is appropriate. In order to help the child, reach his or her full potential, children born with this genetic disorder would most likely need continuous care from a team of parents, therapists, medical and educational experts. Children with cri du chat syndrome are expected to achieve their fullest capacity and can lead to complete and fulfilling lives with early and regular educational support, as well as physical and language therapy.