Cat’s Cry Syndrome: Features and Modification | Genetics

In this article we will discuss about:- 1. Diagnostic Features of Cat’s Cry Syndrome 2. Modification of Cat’s Cry Syndrome 3. Findings.

Diagnostic Features of Cat’s Cry Syndrome:

Some of the following features are not absolute in occurrence, and in that case values in the parentheses are the frequency of occurrence:

i) The name of this syndrome refers to the fact that babies exhibiting it have a peculiar face plaintive viewing with cat­like cry.

ii) Mental, motor function and growth retardation.

iii) Broad-headed microcephaly.

iv) Epicanthic folds.

v) Occular hypertelorisus.

vi) Downward and outwardly sloping palpebral fissures.

vii) Broad face.

viii) Saddle nose.

ix) Micrognathia and outwardly sloping palpebral fissures.

x) Low set malformed ears.

xi) Antimongoloid slant to eyes (64% recorded).

xii) Rotated ears (11% recorded).

xiii) Accessory auricles (9% recorded).

xiv) Microcephaly (92% recorded).

xv) Abnormal larynx (32% recorded).

xvi) Hypotonia (50% recorded).

xvii) Hypertonia (10% recorded).

xviii) Failure to thrive (88% recorded).

xix) Oligophrenia (94 or 97% recorded).

xx) Single palmar crease (45% recorded).

xxi) Distal + Triradius (62% recorded).

xxii) Absent C triradius (70% recorded).

xxiii) Birth rates are low.

xxiv) Gestation time is normal.

Remark:

Lejeune (1964) showed that this chromosomal aberration may be transmitted from parent to child in which a phenotypically normal mother was a balanced translocation carrier involving B4-5 and D1315 groups.

The affected child receives the deleted B5 chromosome but not the chromo­some of the D13-15 group to which the delet­ed portion of the B5 had been translocated. But de Grouchy (1965) showed that the translocation was between B5 and G (21-22) chromosome.

Modification of Cat’s Cry Syndrome:

Some babies with partial deletion of a B chromosome but lacking the cat-cry, proba­bly suffer from a deficient disorder, presum­ably because the deficient chromosome is a 4 instead of 5. According to Hirschhern (1965) this is often referred to as the “defect of midline fusion” syndrome. Here common­ly affected areas are the scalp, nose, lips, palate and, in males, the penis.

Chronic Granulocytic (Myelogenosis) Leukemia and the Philadelphia Chromosome:

Nowen and Hungarford (1960) found that patients with chronic granulocytic leukemia invariably carried a G 21 chromosome whose long arm was shorter than the normal chro­mosome. This chromosome was named the ph I (Philadelphia) chromosome by Though (1961) after the name of the city of this discovery.

Population Incidence:

There seems to be higher frequency of females than males, perhaps reflecting increased fetal mortality of males. No good estimate of the frequency of the 5 p^– syn­drome is available, since most of the patients are not identified, diagnosis requiring a com­plete karyotype analysis.

Though an estimate of the frequency of this syndrome is given as over 1 per cent but less than 10 per cent of the severely mentally retarded patients. Many have IQ scores below 10, and most are insti­tutionalised.

Relation with Maternal Age:

Maternal age is not raised (mean 28.5 years). The sex proportion is abnormal with 62% of cases being female.

Findings In ‘Cri Du Chat’ Syn­drome:

i) Mean maternal age at birth 28.50 yr.

ii) Mean paternal age at birth 31.32 yr.

iii) Mean gestation age 39.90 weeks.

iv) Mean birth weight 2.68 Kg = 5 lb 14 Oz

v) Survival: one case died at 13/yr.

vi) Sex: 23 9 ; 14 Of (data from “Handbook of Molecular Cytology”—Lima-de-Faria.)

Conclusion:

Translocation appears to be the com­mon cause of the defect, an estimated 13 per cent of cases being associated with translocations, described cases have had B/C, B/G and B/D translocations. The high proportion emphasises the importance of unbalanced gamete formation in transloca­ted heterozygotes as a cause of this syndrome.