Prenatal ascertainment of an inherited dup(18p) associated with an apparently normal phenotype

✍ Scribed by Wolff, Daynna J. ;Raffel, Leslie J. ;Ferré, Merry M. ;Schwartz, Stuart

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 287 KB
• Volume: 41
• Category: Article
• ISSN: 0148-7299
• DOI: 10.1002/ajmg.1320410311

✦ Synopsis

Direct two-generation transmission of an unbalanced 18p + chromosome was discovered after amniocentesis. Neither the mother nor the child exhibited apparent physical malformations or mental impairment. Banding analysis suggested a complete 18p duplication. Molecular studies verified the 18p origin of the duplicated material. Only 14 previous cases of duplication 18p have been reported and these exhibited either a normal phenotype or mild and inconsistent abnormalities. The present cases, as well as the review of literature, indicate that duplication 18p is associated with few or inapparent phenotypic abnormalities. KEY WORDS: duplication 18p, chromosome aberration, DNA dosage studies

fifth fingers. The pregnancy continued without complication and a phenotypically normal female was delivered at 39 weeks. Follow-up evaluation of the child was performed at age 2 years. On physical examination, including dermatoglyphic analysis, she was generally within normal limits. Her height and weight were on the 50th and 80th centiles, respectively, and she was normocephalic. The only unusual clinical findings were bilaterally short fifth fingers, similar to the mother, and pre-auricular pits (which were reportedly present in the normal father as well). At age 2 years, the child was developmentally and intellectually normal.

CYTOGENETIC STUDIES

Cytogenetic analysis of GTG-banded amniotic fluid cells demonstrated a fetal karyotype of 46,XX, + 18p + . C-banding results were inconsistent with the 18ph+ variant (Fig. lc) [Fordyce et al., 1983; Dallapiccolla et al., 19861. The father's chromosomes were normal.