Cri-du-chat Syndrome (5p Minus Syndrome)

What causes cri-du-chat syndrome

The condition results from a deletion of genetic material at the end of the short arm of chromosome 5 (5p). The size of the missing piece varies, and larger deletions tend to cause more severe features. Loss of specific genes contributes to particular features: for example, the CTNND2 gene is linked to intellectual disability, and a region near 5p15.3 to the characteristic cry.

• About 85 to 90% of cases are new (de novo) deletions that occur randomly when egg or sperm cells form. Parents of these children have normal chromosomes, and the chance of it happening again is low.
• About 10 to 15% result from a parent carrying a balanced translocation, where chromosome material is rearranged but not lost. These parents have a higher chance of another affected pregnancy, so parental chromosome testing is offered.

The deletion is more often on the chromosome inherited from the father. Nothing parents did during pregnancy causes it.

Signs and symptoms

In babies

• a high-pitched, mewing cry, caused by differences in the larynx and nervous system
• low birth weight and slow growth (failure to thrive)
• low muscle tone (hypotonia)
• feeding and swallowing difficulties, reflux
• a small head (microcephaly) and round face
• wide-set eyes, downward-slanting eye openings, skin folds over the inner eye corners
• a small jaw, low-set ears, and a broad nasal bridge
• single palm creases

In childhood and adulthood

• intellectual disability, usually moderate to severe
• developmental delay, particularly in speech; many children understand more than they can say and use signs or communication devices
• delayed walking, often by age 3 to 6
• behaviors such as hyperactivity, repetitive movements, sensitivity to sound, and self-injury in some
• the face lengthens with age, and the cry usually becomes less distinctive

Associated health problems

• heart defects in some children, see congenital heart defects
• scoliosis and hip problems
• eye problems including strabismus and nearsightedness
• hearing issues and frequent ear infections
• dental problems
• kidney differences, hernias and constipation

Diagnosis

The cry and facial features often prompt testing soon after birth. Diagnosis is confirmed by:

• Chromosomal microarray: detects the deletion and its exact size.
• Karyotype and FISH: to see the deletion and check for translocations.
• Parental testing: to identify a balanced translocation.

Before birth, the deletion can be found by chorionic villus sampling or amniocentesis, and sometimes it is suspected on ultrasound or noninvasive prenatal screening.

Treatment and support

There is no cure, but a coordinated care team helps each child reach their potential:

• Early intervention: from infancy, including physical therapy for motor skills and muscle tone.
• Feeding support: specialist feeding therapy, thickened feeds, and sometimes a feeding tube in early life.
• Speech and language therapy: sign language, picture systems and electronic communication devices.
• Occupational therapy: for daily living skills.
• Behavioral support and, where needed, medicines for hyperactivity or sleep.
• Medical care: heart evaluation (echocardiogram), hearing and eye tests, orthopedic follow-up, dental care.
• Special education services through an individualized education program (IEP).
• Family support: genetic counseling, respite care and connection with support organizations such as the 5p- Society.

Outlook

Life expectancy is close to normal for many people, especially once they pass the first years of life, when heart defects, feeding difficulties and infections are the main risks. Most adults need lifelong support, but many walk, communicate in their own way, enjoy social activities and have happy, engaged lives. Outcomes vary widely with deletion size and early support.

Frequently asked questions

What causes cri-du-chat syndrome?

It is caused by a missing piece of the short arm of chromosome 5. In most families, this happens randomly during the formation of the egg or sperm. In about 1 in 10 cases, a parent carries a balanced chromosome rearrangement, which raises the chance in future pregnancies.

Why do babies with cri-du-chat syndrome cry like a cat?

The high-pitched, mewing cry is thought to result from differences in the structure of the larynx (voice box) and in nerve control of the vocal cords. The distinctive cry usually becomes less noticeable as the child grows.

What is the life expectancy for cri-du-chat syndrome?

Most children survive infancy, and many live well into adulthood. The greatest risks are in the first year, from heart defects, breathing and feeding problems, and infections. With good medical care, life expectancy for many people is near normal.

Can people with cri-du-chat syndrome talk?

Speech is usually significantly delayed. Many children learn some words and phrases, and most understand more than they can say. Sign language, picture boards and communication devices help them communicate effectively.