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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Medical Genetics · Monosomy 5p

Genetics and Diagnostic Testing for Monosomy 5p

At a Glance

Monosomy 5p (Cri du Chat syndrome) is diagnosed using genetic tests like Chromosomal Microarrays or FISH. Symptoms depend on the specific missing genes, such as CTNND2 for development. While most cases occur by chance, parents should receive karyotype testing to check for balanced translocations.

The genetics of Monosomy 5p (Cri du Chat syndrome) can seem like a foreign language. Understanding how your child’s DNA was tested and what those results mean can help you navigate their care with more confidence.

The Basic Blueprint

Every person typically has 46 chromosomes, arranged in 23 pairs. One of those pairs is Chromosome 5. In Monosomy 5p, a piece of the “short arm” (referred to as p) of one of these chromosomes is missing (a deletion) [1][2]. Because your child still has one full copy of chromosome 5, they have one set of these instructions, but both copies are required for the body to develop and function correctly [3].

How the Diagnosis is Made

Doctors use several different “magnifying glasses” to look at chromosomes. You may see these terms on your child’s lab reports:

  • Chromosomal Microarray (CMA): This is now the “gold standard” for diagnosis [4]. It is much more powerful than an older karyotype and can detect very tiny (submicroscopic) deletions [5]. It also tells the doctor exactly where the deletion starts and ends, which is called the breakpoints [6][7].
  • FISH (Fluorescence In Situ Hybridization): This test uses glowing “probes” to see if a specific part of a chromosome is present. It is very accurate for confirming a diagnosis if the doctor already suspects Cri du Chat [8][5].

Why One Deletion Differs from Another

Not all 5p deletions are the same size. The severity of the symptoms (the phenotype) often depends on exactly which genes are missing (the genotype) [9][10].

  • The “Cat-Like” Cry: Research has linked the characteristic high-pitched cry to a very specific, small region on the chromosome that includes the ICE1 gene [10][4].
  • Intellectual Disability: A gene called CTNND2 (delta-catenin) is particularly important for how brain cells connect and communicate [11][12]. When this gene is missing, it is a major contributor to the learning and developmental delays seen in the syndrome [13][14]. If a child has an “atypical” deletion that leaves the CTNND2 gene intact, they may have better communication or motor skills [10][6].

“De Novo” vs. Inherited

In about 85% of cases, the deletion is de novo, meaning it happened by chance and was not passed down from a parent [15]. However, in about 15% of cases, one parent carries a balanced translocation [16]. This means the parent has all their genetic material, but a piece of chromosome 5 has “swapped places” with another chromosome. The parent is healthy, but they have a higher chance of having a child with an unbalanced arrangement (like Monosomy 5p) [17][18].

This is why testing for both parents is often a vital next step. While your child was likely diagnosed using a microarray, you will need a Karyotype test. Microarrays cannot see balanced translocations because there is no “missing” or “extra” genetic material—only a karyotype can visually confirm if pieces have swapped places under a microscope [18].

Common questions in this guide

What is a chromosomal microarray (CMA) for Monosomy 5p?
A chromosomal microarray is the gold standard test for diagnosing Monosomy 5p. It detects very tiny missing pieces on chromosome 5 and tells the doctor exactly where the deletion starts and ends.
Why do some children with Monosomy 5p have different symptoms?
Symptoms vary based on the exact genes missing in the deleted region of chromosome 5. For example, if the CTNND2 gene is preserved, a child may have better communication and motor skills compared to when that specific gene is deleted.
Did I pass Monosomy 5p to my child?
In about 85% of cases, the deletion happens by chance and is not inherited. However, in about 15% of cases, a parent carries a balanced translocation, which increases the chance of passing on an unbalanced chromosome.
Why do parents need a karyotype test if our child had a microarray?
While microarrays are excellent for finding missing genetic material in a child, they cannot detect balanced translocations. A karyotype test is needed to visually confirm if pieces of a parent's chromosomes have swapped places.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Did my child's testing show a simple deletion, or is there an 'unbalanced translocation' involved?
  2. 2.Can you confirm if the CTNND2 gene is included in my child's deleted region, and what does that mean for their developmental outlook?
  3. 3.What is the specific size of my child's deletion in megabases (Mb), and how does this compare to the 'typical' size for Cri du Chat syndrome?
  4. 4.Since we are planning for the future, should both parents have a high-resolution karyotype to rule out a balanced translocation?
  5. 5.Were any other 'cryptic' imbalances or extra pieces of chromosomes found during the microarray testing?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Pleomorphic Parotid Adenoma in a Child Affected with Cri du Chat Syndrome: Clinical, Cytogenetic, and Molecular Analysis.

    Danesino C, Biglioli F, Moneghini L, et al.

    International journal of molecular sciences 2024; (25(19)) doi:10.3390/ijms251910664.

    PMID: 39408992
  2. 2

    Cri du chat syndrome patients have DNA methylation changes in genes linked to symptoms of the disease.

    Holland P, Wildhagen M, Istre M, et al.

    Clinical epigenetics 2022; (14(1)):128 doi:10.1186/s13148-022-01350-3.

    PMID: 36242045
  3. 3

    Long-Term Follow-Up on Bilateral Posterior Hypothalamic Deep Brain Stimulation for Treating Refractory Aggressive Behavior in a Patient with Cri du Chat Syndrome: Analysis of Clinical Data, Intraoperative Microdialysis, and Imaging Connectomics.

    López Ríos AL, Germann J, Hutchison WD, et al.

    Stereotactic and functional neurosurgery 2022; (100(5-6)):275-281 doi:10.1159/000526871.

    PMID: 36446334
  4. 4

    Copy Number Variation Analysis of 5p Deletion Provides Accurate Prenatal Diagnosis and Reveals Candidate Pathogenic Genes.

    Chu G, Li P, Wen J, et al.

    Frontiers in medicine 2022; (9()):883565 doi:10.3389/fmed.2022.883565.

    PMID: 35911393
  5. 5

    [Improved identification for 5p deletion syndrome and partial trisomy 11q presented in a fetus by SNP array].

    Shi S, Pan G, Yang Y, et al.

    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 2016; (33(2)):195-9 doi:10.3760/cma.j.issn.1003-9406.2016.02.015.

    PMID: 27060314
  6. 6

    Cri-du-Chat Syndrome: Revealing a Familial Atypical Deletion in 5p.

    Almeida VT, Chehimi SN, Gasparini Y, et al.

    Molecular syndromology 2023; (13(6)):527-536 doi:10.1159/000524371.

    PMID: 36660031
  7. 7

    Prenatal diagnosis of Cri-du-Chat syndrome with concomitant distal trisomy 10q syndrome in one fetus with ultrasound anomalies.

    He JP, Qian Y, Liu WJ, et al.

    Taiwanese journal of obstetrics & gynecology 2021; (60(2)):318-323 doi:10.1016/j.tjog.2021.01.010.

    PMID: 33678334
  8. 8

    [Genetic analysis of a case with atypical neonatal Cri-du-chat syndrome].

    He W, Chen H, Mu H, Li J

    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 2018; (35(1)):104-106 doi:10.3760/cma.j.issn.1003-9406.2018.01.024.

    PMID: 29419873
  9. 9

    Deep Phenotyping and Genetic Characterization of a Cohort of 70 Individuals With 5p Minus Syndrome.

    Nevado J, Bel-Fenellós C, Sandoval-Talamantes AK, et al.

    Frontiers in genetics 2021; (12()):645595 doi:10.3389/fgene.2021.645595.

    PMID: 34394178
  10. 10

    Multigenerational autosomal dominant inheritance of 5p chromosomal deletions.

    Zhang B, Willing M, Grange DK, et al.

    American journal of medical genetics. Part A 2016; (170(3)):583-93 doi:10.1002/ajmg.a.37445.

    PMID: 26601658
  11. 11

    δ-Catenin Regulates Spine Architecture via Cadherin and PDZ-dependent Interactions.

    Yuan L, Seong E, Beuscher JL, Arikkath J

    The Journal of biological chemistry 2015; (290(17)):10947-57 doi:10.1074/jbc.M114.632679.

    PMID: 25724647
  12. 12

    Roles and regulation of δ-catenin in tumorigenesis and neuronal diseases.

    Zhang Y, Xie K, Jiang T

    Frontiers in cell and developmental biology 2025; (13()):1559059 doi:10.3389/fcell.2025.1559059.

    PMID: 40213389
  13. 13

    A child with autism, behavioral issues, and dysmorphic features found to have a tandem duplication within CTNND2 by mate-pair sequencing.

    Miller DE, Squire A, Bennett JT

    American journal of medical genetics. Part A 2020; (182(3)):543-547 doi:10.1002/ajmg.a.61442.

    PMID: 31814264
  14. 14

    Characterization of CTNND2-related neurodevelopmental disease, phenotype-genotype spectrum and WNT dynamics in early neurogenesis.

    Shahsavani M, Wincent J, Reiter R, et al.

    Research square 2025; doi:10.21203/rs.3.rs-8224288/v1.

    PMID: 41502569
  15. 15

    Prenatal diagnosis of 5p deletion syndrome: Report of five cases.

    Mak ASL, Ma TWL, Chan KYK, et al.

    The journal of obstetrics and gynaecology research 2019; (45(4)):923-926 doi:10.1111/jog.13911.

    PMID: 30932301
  16. 16

    An uninformative NIPT as an early indicator of cri-du-chat due to a chromosomal 5;18 translocation-An atypical presentation of a rare cytogenetic phenomenon.

    Shukla D, Dinunzio M, Colaiacovo S, et al.

    Clinical case reports 2023; (11(8)):e7732 doi:10.1002/ccr3.7732.

    PMID: 37529133
  17. 17

    Three Offspring with Cri-du-Chat Syndrome from Phenotypically Normal Parents.

    Alkaya DU, Karaman B, Tüysüz B

    Molecular syndromology 2020; (11(2)):97-103 doi:10.1159/000506892.

    PMID: 32655341
  18. 18

    Clinical features and genetic analysis of a family with t(5;9) (p15;p24) balanced translocation leading to Cri-du-chat syndrome in offspring.

    Zhao J, Chen P, Ren Y, et al.

    Frontiers in genetics 2025; (16()):1550937 doi:10.3389/fgene.2025.1550937.

    PMID: 40406061

This page explains genetic testing terminology for educational purposes. Always consult your genetic counselor or pediatrician to interpret your child's specific laboratory reports.

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