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Definition: Deletion of the distal segment of the short arm of chromosome number 8.

Prevalence: 15 reported cases.

Etiology: De novo deletion, or balanced familial translocation.

Associated anomalies: Growth delay, mental retardation, abnormal facies, microcephaly, congenital heart disease. The present case has diaphragmatic hernia.

Prognosis: Depends on size of deletion. All have severe mental retardation.

Recurrence risk: Unknown; may be as high as 1%.

Management: Standard obstetrical care.

MESH Chromosome-aberrations BDE 2450 POS 3691 ICD9 758.3 CDC 758.380

Introduction

Deletion of the distal segment of the short arm of the 8^th chromosome was first reported in 1973. Subsequent to this, 14 additional cases of 8p- syndrome have been described in the literature^1-3. The clinical features have been reviewed by Pecile et al. In the postnatal period, the 8p- syndrome is characterized by growth delay, mental retardation, abnormal facies, and congenital heart disease.

The present report describes a fetus in whom the prenatal diagnosis of 8p- syndrome was made.

Case report

A 27-year-old white woman was referred to the prenatal diagnosis center because of a borderline elevation of maternal serum alpha-fetoprotein of 2.0 multiples of the median. The patient"s clinical dates were based on a sure last menstrual period. Ultrasound showed a fetus with an estimated growth delay of approximately 3 weeks. The fetal heart was shifted to the right side of the chest, suggestive of diaphragmatic hernia (fig. 1). A ventricular septal defect was present and the fetus was noted to have a large stomach. Percutaneous umbilical blood sampling showed a deletion of the distal short arm of chromosome 8. Both parental karyotypes were studied and found to be normal. The chromosome abnormality was 46 XX, del (8) (p 23.1 p. 23.2). The patient elected termination of pregnancy.

Figure 1: Axial section of the chest at the level of the 4-chamber

Autopsy

An autopsy performed on the fetus showed multiple congenital defects (fig. 2). The face was abnormal with telecanthus and a broad-based nose, and the ears were posteriorly rotated. The fingernails and toenails were broad and spoon-shaped. A left posterior diaphragmatic hernia with small intestine in the left chest and a hypoplastic left lung were found. There was an ostium primum atrial septal defect as well as an endocardial cushion defect. No other abnormalities were noted.

Figure 2: Fetus with 8p- syndrome. Note the low-set ears, low nasal

Discussion

This case reemphasizes the association of fetal aneuploidy with sonographic findings of growth delay and dysmorphology. The spectrum of fetal affectation by 8p- deletion may depend in part on where the actual chromosome breakpoints occur.

Clinical findings

These infants present with microcephaly, a narrow head with high forehead, epicanthal folds, low nasal bridge and micrognathia. Aside from ventricluar septal defects, they may have pulmonary stenosis. Growth retardation continues after birth as failure to thrive. Mental retardation and speech difficulties are also present.

This chromosomal abnormality has not been previously reported in association with diaphragmatic hernia.

Recurrence risk

There is insufficient data on 8p- deletion in the literature to determine recurrence risks for subsequent offspring. If the recurrence risk is similar to other de-novo chromosomal abnorma­lities, the recurrence risk is estimated to be near 1%. Prenatal diagnosis should be offered in any subsequent pregnancy.

References

1. Lubs HA, Lubs ML: New cytogenetic techniques applied to a series of children with mental retardation. In T. Casperson, L. Zach (eds.)Chromosome identification technique and application in biology and medicine. Nobel Symposia 23. New York, Academic Press, 241-250,1973.

2. Pecile V, Petroni MG, Fertz MC, Filippi G: Deficiency of distal 8p-: report of two cases and review of the literature. Clin Genet 37:271-278,1990.

3. Blennow E, Brondum-Nielsen K: Partial monosomy 8p: minimal dysmorphic signs. J Med Genet 27:327-329,1990.