Cri-du-chat Syndrome Workup

Updated: Jun 09, 2017
  • Author: Mithilesh K Lal, MD, MBBS, MRCP, FRCPCH, MRCPCH(UK); Chief Editor: Maria Descartes, MD  more...
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Workup

Laboratory Studies

Conventional cytogenetic studies

The size of the 5p deletion may vary from the entire short arm to only 5p15. A small deletion of 5p may be missed using a conventional cytogenetic technique.

High-resolution cytogenetic studies

These look for a small deletion of 5p.

Fluorescence in situ hybridization (FISH)

Molecular cytogenetic studies using FISH allow the diagnosis to be made in patients with very small deletions. FISH uses genetic markers that have been precisely localized to the area of interest.

The absence of a fluorescent signal from either the maternal or paternal chromosome 5p regions indicates monosomy for that chromosomal region.

Fluorescent in situ hybridization (FISH) study of Fluorescent in situ hybridization (FISH) study of a patient with cri-du-chat syndrome. FISH photograph shows deletion of a locus-specific probe for the cri-du-chat region. Spectrum orange color represents chromosome 5–specific signal and spectrum green is cri-du-chat locus signal. Absence of a green signal indicates monosomy for that region (left, interphase cell; right, metaphase chromosome spread).

A rare case of cri-du-chat syndrome born to a woman carrying a t(11;22)(q23;q11.2) has been diagnosed using FISH-based preimplantation genetic diagnosis. [14]

Chromosome comparative genomic hybridization (CGH)

Chromosome CGH is capable of screening the entire genome for DNA copy-number alterations in a single hybridization. The resolution is limited to approximately 5-10 Mb. The results cannot be directly mapped onto the genome sequence.

Microarray CGH

Microarray CGH uses array elements made from large-insert genomic clones, such as BACs and phage artificial chromosomes (PACs).

This method has sufficient measurement precision to permit reliable detection of single-copy aberrations affecting individual clones.

SNP-based test

A study by Wapner et al indicated that a single-nucleotide polymorphism (SNP)-based prenatal test can accurately screen prenatally for cri-du-chat syndrome and other microdeletion syndromes. The study, which employed 358 plasma samples from pregnant women and 111 artificial plasma mixtures, used a massively multiplexed polymerase chain reaction and the Next-generation Aneuploidy Test Using SNPs (NATUS) algorithm. The detection rate for cri-du-chat syndrome was 100% (24 out of 24 samples), with a 0.24% false-positive rate. Detection rates were also 100% for Prader-Willi, Angelman, and 1p36 deletion syndromes and 97.8% for 22q11.2 deletion syndrome. [15]

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Imaging Studies

See the list below:

  • Skeletal radiography
    • Microcephaly, retromicrognathia
    • Cranial base malformations (reduced cranial base angle and malformed sella turcica and clivus)
    • Disproportionately short third, fourth, and fifth metacarpals and disproportionately long second, third, fourth, and fifth proximal phalanges (common)
  • MRI
    • Atrophy of the brainstem, atrophic middle cerebellar peduncles and cerebellar white matter
    • Pontine hypoplasia has been described [16]
    • Possible hypoplasia of cerebellar vermis with enlargement of the cisterna magna and fourth ventricle
  • Echocardiography - Used to rule out structural cardiac malformations
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Other Tests

See the list below:

  • Swallowing study to assess for feeding difficulty
  • Comprehensive evaluation for receptive and expressive language (Most children have better receptive language than expressive language.)
  • Developmental testing, referral to early intervention, and appropriate school placement
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Procedures

See the list below:

  • Gastrostomy in infancy to protect the airway in patients with major feeding difficulties
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