Partial chromosome 4 trisomy

Clinical manifestations of trisomy 4p syndrome

Trisomy 4p syndrome is a distinct clinical entity which was noted almost a quarter century ago by Wilson et al. [71] and later was delineated by Gonzalez and colleagues [29]. The variation in the length of duplicated segment usually associated with monosomy of other genetic material which has resulted in confusion and as a result a so-called 4p syndrome could not be recognized without cytogenetic analysis. We wish to draw the attention of clinicians to this subject by presenting the description of over 75 cases including one from our clinic and stress the point that molecular approaches are imperative to characterize this anomaly. After extensive review, it appears that patients retaining at least the distal two-thirds to the entire short arm share an overlapping phenotypic expression that constitutes pure trisomy 4p syndrome which includes prominent glabella, bulbous nose with flat or depressed nasal bridge, retrognathia, pointed chin, short neck with low hairline, enlarged ears with abnormal helix and antihelix, rocker-bottom feet with prominent heel. Arachnodactyly and camptodactyly. Molecular characterization of 4p is imperative. We have also included an extensive bibliography for clinicians who may find it useful as a single reference source for evaluating their future cases.

CONCLUSION

The 4p-syndrome is a distinct entity but without cytogenetic evaluation, the syndrome can not be recognized.

Suggested assignment of peptidase S (PEPS) to 4p11-4q12 by exclusion using gene dosage, accounting for variability in fibroblasts

A colorimetric assay using leucyl-beta-napthylamide hydrochloride as substrate and fast garnet GBC as the color reagent was developed for these regional mapping studies of peptidase S (PEPS). PEPS activity was measured in white blood cells from three patients with Wolf-Hirschhorn syndrome (4p-) and 50 controls. The enzyme activity of the three patients, mean 0.097 +/- 0.060 (SD) did not exhibit a significant dosage effect compared to the controls, mean 0.125 +/- 0.060 (SD) mIU/mg protein. Peptidase activity was compared among five fibroblast control lines and eight lines with chromosome 4 aberrations. There was no significant difference found among the 128 samples from aberrant lines, mean of partial monosomies = 0.095 +/- 0.049 (SD) and mean of partial trisomies = 0.084 +/- 0.046 (SD) and the 79 samples from control lines, mean = 0.092 +/- 0.043 (SD) mIU/mg protein. Degree of confluence, site of biopsy, and sex and age of donor did not affect PEPS activity in fibroblasts but generation number did (r = 0.367, P = 0.001). No gene dosage was found in the white blood cells or fibroblast lines studied. The locus for PEPS is therefore mapped to 4p11 leads to 4q13 by exclusion. Combining these data with those previously reported, the suggested assignment for the PEPS locus is the 4p11 leads to 4q12 segment of chromosome 4.