Congenital Anomalies and Anthropometry of 42 Individuals with Deletions of Chromosome 18q

Abstract

We have evaluated 42 subjects with deletions of 18q at our institution. This is the largest number of individuals with this chromosome abnormality studied by one group of investigators. Here we report the physical findings in these individuals. We have compared our findings with those of previously reported cases and have found a significantly different incidence of several minor anomalies in our subjects. We also describe here several anomalies not previously reported in individuals with deletions of 18q, including short frenulum, short palpebral fissures, disproportionate short stature, overlap of second and third toes, and a prominent abdominal venous pattern. Characteristics found in subjects were analyzed for correlation with cytogenetic breakpoints. Several traits were found to correlate with the extent of the deletion. Large deletions were associated with significantly decreased head circumference and ear length as well as the presence of proximally placed and/or anomalous thumbs. Individuals with the smallest deletions were more likely to have metatarsus adductus. Although relatively few genotype/phenotype correlations were apparent, these data demonstrate that correlations with breakpoint are possible. This implies that more correlations will become evident when the more precise molecularly based genotyping is completed. These correlations will identify critical regions on the chromosome in which genes responsible for specific abnormal phenotypes are located. Am. J. Med. Genet. 85:455-462, 1999.

Delineation of complex chromosomal rearrangements: evidence for increased complexity

“…Deletions of the long arm of chromosome 18 occur in approximately 1 in 40,000 live born infants (Cody et al 1999), with even quite large deletions in this region of the genome being compatible with life. Cody et al (1999) studied 42 individuals with deletions of chromosome 18q, comparing phenotypic findings among these individuals, and suggesting that deletions of 18q may represent a contiguous gene deletion syndrome.…”

“…Cody et al (1999) studied 42 individuals with deletions of chromosome 18q, comparing phenotypic findings among these individuals, and suggesting that deletions of 18q may represent a contiguous gene deletion syndrome. Our patient had two noncontiguous interstitial deletions, with the loss of approximately 18 Mb DNA in total.…”

Prenatal diagnosis of del(15)(q26.1) and del(18)(q21.3) due to an unbalancedde novo translocation: ultrasound, molecular cytogenetic and autopsy findings

“…The fetus reported here did not have other major malformations of the 18q-spectrum such as congenital heart defects or cleft lip and palate (Wilson et al, 1979). The additional autopsy ®ndings in our patient were not highly speci®c for anomalies described in other reports as part of the 18q21.3 spectrum (Kline et al, 1993, Cody et al, 1999. It is dif®cult to decide whether some of the external clinical anomalies in this fetus, such as malformed ears,¯at nasal bridge or clubfeet, were part of the spectrum of the 18q-syndrome.…”

“…Deletions of the distal part of chromosome 18 (18q21->qter) are among the most frequent human deletion syndromes with over 100 cases reported (Schinzel, 1984) and an estimated frequency of 1/ 40 000 among live births (Cody et al, 1999). The most common breakpoint on chromosome 18 appears to be 18q21.…”

“…This indicates that renal anomalies are a frequent ®nding in chromosomal disorders (Chen et al, 1999, Farina et al, 1999. Various genitourinary malformations, including unilateral renal agenesis, are part of the spectrum of the 18q-deletion syndrome in live births (Cody et al, 1999). This chromosomal deletion syndrome is one of the most frequent partial aneusomy disorders, and the spectrum of clinical anomalies is well studied (Strathdee et al, 1997).…”