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A syndrome associated with a high-pitched,
cat-like cry in the newborn period, severe mental retardation, facial
anomalies, scoliosis, muscular hypotonia and congenital cardiac defects.
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Cri-du-Chat Syndrome; Lejeune Syndrome, Deletion of Short Arm of
Chromosome 5; Monosomy 5p.
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First described in 1963 by the French pediatrician Jérôme Jean L.M.
Lejeune.
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Appears to be the most common human deletion syndrome, with an
incidence of 1 in 15,000 to 1 in 50,000 live births. The frequency in patients
with profound mental retardation (IQ<20) may be as high as 0.3%. A slight
female predominance has been reported.
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The syndrome arises from a partial or total deletion of
the short arm of chromosome 5. A loss of the critical 5p15.2 region gives rise
to most of the clinical features. The vast majority of cases are sporadic
resulting from new mutations. Some arise from unbalanced translocations or
parental chromosomal rearrangements. The severity of the syndrome is related to
the extent of the chromosome deletion.
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Based on the clinical picture plus molecular cytogenetic
confirmation of 5p deletion with fluorescent in situ hybridization (FISH),
which is considered the gold standard.
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The name of the syndrome derives from the characteristic,
high-pitched cry in infancy, which sounds similar to the mewing of a cat and is
considered diagnostic for this disorder. The abnormal cry is mainly caused by
anatomical anomalies of the larynx (long, curved and floppy epiglottis,
laryngeal hypoplasia, laryngomalacia, asymmetric vocal cords, anterior
approximation of the vocal cords with a large posterior commissure), however,
in some patients the larynx was found to be structurally normal, which explains
why some researchers believe that there may also be a neurological component
involved in the abnormal cry. Mental retardation is most often severe. Central
nervous findings include marked brainstem atrophy (mainly at the level of the
pons) and cerebellar hypoplasia also involving the middle cerebellar peduncles.
Generalized muscular hypotonia, poor sucking reflex, and respiratory distress
may result in failure to thrive, which in combination with the commonly present
intrauterine growth retardation results in postnatal growth retardation. The
head usually is microcephalic with a round face due to full cheeks, downward
slanting of the palpebral fissures, hypertelorism, low-set ears, depressed
nasal bridge, microand/or retrognathia with a high-arched, narrow palate
(cleft palate has also been described), and macrostomia. Up to 30% of these
patients have congenital cardiac defects (most commonly atrial and/or
ventricular septal defects, tetralogy of Fallot, pulmonary stenosis, and patent
ductus arteriosus). Abdominal findings may include malrotation, megacolon, and
inguinal hernias. The urogenital system may also be affected and findings
include renal anomalies (e.g., renal agenesis, horsehoe kidney,
hydronephrosis), hypospadias, cryptorchidism and testicular atrophy
(although spermiogenesis is most often with intact). Skeletal features that
have been reported are scoliosis, clubfoot, clinodactyly, and syndactyly of
fingers and toes. Abnormal dermatoglyphics (e.g., simian crease) and premature
graying of the hair may be present. Severely destructive behavioral problems
(agression, self-mutilation) have been described repeatedly. Many patients die
in early childhood mainly from ...