Human chromosomal deficiency: the 4p--syndrome

An epidemiological study of Wolf-Hirschhorn syndrome: life expectancy and cause of mortality

OBJECTIVE

Early research into Wolf-Hirschhorn syndrome (WHS) described a high mortality and no relationship between deletion size and phenotype. This may need to be revised in the light of improved cytogenetic resolution and medical care. We have collected epidemiological data to allow the calculation of birth incidence and mortality figures. In addition, we have investigated the possibility of a relationship between deletion size and mortality.

METHOD

Information relating to past and present cases diagnosed in the UK was collected by multiple ascertainment.

RESULTS

A total of 159 cases were collected. The status (alive or dead) was determined for 146, of whom 96 are alive, 37 had died, and 13 were detected on prenatal diagnostic tests. A minimum birth incidence of 1 in 95 896 was calculated. The crude infant mortality rate was 17% (23/132) and in the first two years of life the mortality rate was 21% (28/132). Cases with large de novo deletions (proximal to and including p15.2) were more likely to have died than those with smaller deletions (odds ratio=5.7, 95% CI=1.7-19.9) after adjusting for age. A comparison of survival curves for de novo deletions and translocations did not show a statistically significant difference (p=0.11). The median survival time for de novo deletions was 34+ years while for translocation cases it was 18+ years.

CONCLUSIONS

The mortality rate is lower than previously reported. There is a statistically significant relationship between deletion size and overall risk of death in de novo deletion cases. The difference in survival curves between de novo deletions and translocations is not statistically significant.

Ophthalmic features of chromosome deletion 4p- (Wolf-Hirschhorn syndrome)

By using the Giemsa banding technique we identified three patients with chromosome deletion 4p-. All had anterior segment anomalies, exotropia, blepharoptosis, antimongoloid palpebral fissures, hypertelorism, and disk abnormalities. One patient (Case 1) had Rieger's anomaly. Some clinical features in patients with 4p- are similar to those in patients with chromosome deletion 5p-, cri-du-chat syndrome, although 4p- individuals do not have the distinctive cry. The ocular features which distinguish 4p- from other deletions include normal tearing, some degree of blepharoptosis, and the preponderance of anterior segment signs.

The Wolf-Hirschhorn (4p-) syndrome

In a review of 43 cases, the phenotypic spectrum of the Wolf-Hirschhorn syndrome is analyzed and the frequency of clinical anomalies is tabulated. The characteristic features are intrauterine growth retardation, severe psychomotor retardation, typical facies, and various major and minor congenital anomalies suggestive of a midline fusion defect. Diagnosis is established by karyotyping- deletion of the short arm of chromosome No. 4. All cases so far reported are de novo occurrences with no sibling involvement and normal parents. Prognosis is poor, with death in the first 2 years of life in 34% of cases, usually due to cardiac decompensation or infection. Psyhomotor retardation is profound, so that heroic medical efforts probably need to be reconsidered.

Derivative chromosomal structures from a ring chromsome 4

This report describes the results from cultured lymphocytes studied at metaphase, anaphase, and interphase from an individual with a ring chromosome 4. A ring was present in 90.1% of metaphases. Special attention was directed towards the occurrence of derivative chromosomal structures, such as partially duplicated and triplicated rings, tricentric rings, chains of 3 interlocked rings, rod-shaped chromosomes, "pulverized" rings, and others. The clinical features of the individual (small stature and impaired mental development, hypoplastic thumbs, ptosis palpebrae hypoplastic external male genitalia, abnormal dermatoglphic pattern) did not conform to a specific phenotype.