1602
Also known as chromosome 5p deletion syndrome, 5p? syndrome or Lejeune’s syndrome.
A rare genetic disorder due to chromosome deletion on chromosome 5.
The name refers to the characteristic cat-like cry of affected children.
The condition affects an estimated 1 in 50,000 live births.
It affects all ethnicities and is more common in females by a 4:3 ratio.
The characteristic cry of affected infants, which is similar to that of a meowing kitten, is due to laryngeal and nervous system abnormalities.
About one third of children lose the cry by age of 2 years.
Other symptoms include:
feeding problems because of difficulty in swallowing and sucking;
low birth weight and poor growth
severe cognitive, speech and motor disabilities
behavioral problems such as hyperactivity, aggression, outbursts and repetitive movements
unusual facial features, which may change over time
excessive drooling
small head and jaw
widely-spaced eyes
skin tags in front of eyes
hypotonia,
a round face with full cheeks,
Epicanthal folds,
down-slanting eyelids.
strabismus,
flat nasal bridge,
down-turned mouth,
low-set ears,
short fingers,
single palmar creases
cardiac defects (ventricular septal defect [VSD], atrial septal defect, patent ductus arteriosus)
tetralogy of Fallot.
Infertility is not associated with Cri du chat.
Patients have difficulties communicating.
Less frequent associated findings include: cleft lip and palate, preauricular tags and fistulas, thymic dysplasia, intestinal malrotation, megacolon, inguinal hernia, dislocated hips, cryptorchidism, hypospadias, rare renal malformations, clinodactyly of the fifth fingers, talipes equinovarus, pes planus, syndactyly of the second and third fingers and toes, oligosyndactyly and hyperextensible joints, and various dermatoglyphics, including transverse flexion creases, distal axial triradius, increased whorls and arches on digits and a single palmar crease.
In late childhood and adolescence manifestations include significant intellectual disability, microcephaly, coarsening of facial features, prominent supraorbital ridges, deep-set eyes, hypoplastic nasal bridge, severe malocclusion and scoliosis.
Affected females reach puberty, develop secondary sex characteristics and menstruate at the usual time and have normal genital tracts.
The testes are often small, but spermatogenesis is thought to be normal.
Some patients are very high-functioning, with mostly the exception of mild learning difficulties, and do not have speech difficulties, although they may have milder facial features and a high-pitched voice due to their condition.
It is due to a partial deletion of the short arm of chromosome number 5, also called 5p monosomy or partial monosomy.
Approximately 90% of cases result from a sporadic, or randomly occurring, de novo deletion.
The remaining 10-15% are due to unequal segregation of a parental balanced translocation where the 5p monosomy is often accompanied by a trisomic portion of the genome, and may have more severe disease than those with isolated monosomy of 5p.
Most cases involve total loss of the most distant 10-20% of the material on the short arm.
Other rare cytogenetic aberrations including interstitial deletions, mosaicisms, rings and de novo translocations occur in fewer than 10% of cases.
The deleted chromosome 5 is paternal in origin in about 80% of de novo cases.
Loss of a small region in band 5p15.2 correlates with all the clinical features of the syndrome with the exception of the catlike cry.
The catlike cry is associated with band 5p15.3
Two noncontiguous critical regions contain genes involved in this condition.
Diagnosis is easily observed, based on the distinctive cry and accompanying physical problems.
Prenatally the deletion of the cri du chat related region in the p arm of chromosome 5 can be detected.
Children may be treated by speech, physical and occupational therapists.