What is 5p Deletion Syndrome (Cri du Chat Syndrome)? [Explained by a Doctor]

Introduction

For pregnant women considering non-invasive prenatal testing (NIPT), obtaining accurate information about chromosomal abnormalities is a crucial factor in making decisions.

In this article, we will provide an easy-to-understand explanation of 5p deletion syndrome (Cri du Chat syndrome) from a physician's perspective, based on evidence from the latest academic papers.

Basic Knowledge

5p deletion syndrome (Cri du Chat syndrome) is a genetic disorder caused by a partial deletion of the short arm of chromosome 5 (5p).

The name of this syndrome is derived from the characteristic high-pitched cry resembling a cat's mewing in the newborn period. It is also called Cri du Chat syndrome and is one of the chromosomal deletion syndromes first reported by Dr. Lejeune et al. in 1963. *1,2

◇ Frequency and Incidence

The incidence of 5p deletion syndrome is estimated to be 1 in 15,000 to 50,000 live births, making it a relatively common chromosomal deletion syndrome. *2,3
The incidence is slightly higher in females, and it has been identified in all races. *2
It is estimated to account for 1 in 350 individuals with intellectual disabilities. *4

◇ Causes and Pathogenesis

In most cases (80-90%), this chromosomal abnormality is a de novo occurrence, meaning it occurs by chance during fetal development with no abnormalities in either parent. *1
Specifically, it is caused by the accidental breakage of a chromosome during the formation of sperm or egg cells.

Symptoms and Characteristics

◇ Symptoms in the Newborn Period

The most characteristic symptom of 5p deletion syndrome is a high-pitched cry observed in the newborn and infant periods. *1,2,3
This cat-like cry is caused by laryngeal malformation, specifically anatomical changes such as a small, floppy epiglottis and a hypoplastic, narrow larynx. *1

Other newborn characteristics include: *1,3

• • Low birth weight (average 2,614g)
• • Microcephaly
• • Hypotonia
• • Poor sucking
• • Failure to thrive

◇ Facial and Physical Features

Individuals with 5p deletion syndrome show distinctive facial features. *3

• • Micrognathia (96.7%)
• • Epicanthal folds (90.2%)
• • Broad nasal bridge (87.2%)
• • Round face (83.5%)
• • Hypertelorism (widely spaced eyes) (81.4%)
• • Downturned corners of the mouth (81.0%)
• • Low-set ears (69.8%)

◇ Developmental and Behavioral Characteristics

Severe psychomotor developmental delay is observed in all cases. *3
However, it has been reported that improvements can be expected through early education and rehabilitation programs. *3

According to Italian registry data, 50% of patients achieve independent walking by 3 years of age and can feed themselves using a spoon by 3.5 years of age.
In addition, 25% of patients are reported to be able to speak short sentences by 4.5 years of age. *3

Behaviorally, hyperactivity, self-injury, repetitive behaviors, and hypersensitivity to sound may be observed, but many patients exhibit a gentle and affectionate personality. *3

Prognosis and Quality of Life

◇ Survival Rate and Prognosis

The newborn period and early infancy are the most critical times.
It is estimated that 75% of deaths occur within the first month of life, and 90% occur within the first year. *1,2
However, survival expectations after surviving this period are high, with patients reported to live over 50 years of age. *3

◇ Factors Affecting Prognosis

• • Size and location of the deletion: Larger deletions tend to present with more severe symptoms. *1,3
• • Early diagnosis and early intervention: Appropriate treatment and rehabilitation can lead to improvements in prognosis. *1,3
• • Presence of complications: The presence of congenital heart disease or intractable epilepsy significantly affects the prognosis. *4

◇ Growth and Development

Specific growth charts have been established, and pre- and post-natal growth delays are characteristic. Weight tends to stay around the 2nd to 5th percentile throughout life, whereas height is known to be less affected than weight. *3

Treatment and Care

Because brain development is affected early in the fetal period in 5p deletion syndrome, there is currently no fundamental cure.
However, early rehabilitation programs have been proven to improve patient prognosis and social adaptation. *1,3
Treatment primarily focuses on symptomatic therapies and comprehensive care for each symptom.

◇ Management in the Newborn and Infant Periods

• • Breastfeeding is possible, and intensive care is rarely required. *1,3
• • For newborns with sucking or swallowing difficulties, physical therapy is initiated from the first week of life. *1

◇ Rehabilitation and Developmental Support

• • Physical therapy, psychomotor training, and speech therapy are recommended.
• • Hearing evaluations: Since sensorineural hearing loss is frequently associated, regular hearing tests are required for all affected children. *1,3

Summary

5p deletion syndrome is a chromosomal abnormality syndrome caused by a deletion on the short arm of chromosome 5, mainly characterized by a distinctive cry, growth and developmental delays, and specific facial features.
Although there is no fundamental cure, it is a condition where early diagnosis and early intervention can be expected to improve the prognosis.

If a 5p deletion is detected in a prenatal test, it is important to receive comprehensive information through genetic counseling and establish an appropriate management and support system in cooperation with specialized medical institutions.

To improve the patient's quality of life, comprehensive care involving collaboration among healthcare professionals, educators, and family members is essential.

\ Learn the risk of 5p deletion syndrome (Cri du Chat syndrome) /

Click here for details on NIPTApplication / Kit Purchase