Diagnosis and work-up for Cri du Chat Syndrome

The high-pitched, monotone, cat-like cry is the basis of diagnosis during infancy. Other signs include poor muscle tone, microcephaly, micrognathia, hypertelorism, epicanthic folds and mental retardation. Chromosomal testing of the embryo, referring to when the child is still in the womb of the mother is a means of testing the syndrome. A diagnostic expert can perform tests on two samples in this stage, (1) chronic villus sampling (CVS), wherein a tissue sample from outer part of the sac where the child grows is tested and (2) amniocentesis, wherein a sample of amniotic fluid is tested.

After birth, a physical examination of the infant can disclose some abnormalities such as inguinal hernia, diastasis recti, separated abdominal muscles, or abnormally folded ears. An X-ray of the skull reveals an abnormal angle at the bottom. Some of the laboratory tests and tests that are performed for the diagnosis of the syndrome include
Conventional cytogenetic studies: The amount of the deleted chromosome differs from only 5p15 to the whole of the short arm. These studies are unable to detect a small deletion, but they are very useful.

High-resolution cytogenetic studies: Since small deletions are unable to be detected by conventional cytogenetic studies, high-resolution cytogenetic studies were performed to detect them.

Fluorescence in situ hybridization (FISH)

Chromosome comparative genomic hybridization (CGH) (http://cri-du-chat-syndrome.blogspot.com/)

Microarray CGH: This method employs array elements that are prepared from large-insert genomic clones like BACs or phage artificial chromosomes (PACs).

Apart from the chromosomal studies, imaging studies can also be helpful.

Skeletal radiography

MRI: This method is employed to detect atrophic brainstem, middle cerebellar peduncles or cerebellar white matter, hypoplasia of cerebellar vermis along with extra-growth of cisterna magna and fourth ventricle.

Echocardiography: This technique is employed to check if there are any structural cardiac abnormalities.

The other tests include swallowing study, developmental testing and evaluation of receptive and expressive language.