Trisomy 4 pter-q12 and monosomy of chromosome 13 pter-q12 in a male with deficiency of all blood lymphocyte populations

A six-year-old male presented with multiple congenital anomalies, mental re tardation, developmental delay, and an increased frequency of upper and low er respiratory infections and deficiency of all blood lymphocyte population s. Chromosome analysis showed an unbalanced translocation involving chromos omes 4 and 13, leading to partial trisomy for 4pter-q12 and partial monosom y for 13pter-q13 [karyotype, 46, XY,+der(4)t(4; 13)(q12;q12),-13)]. The mot her is the carrier of a balanced translocation involving chromosomes 4 and 13, The translocation is known to be segregating for three generations in t his family. The child was found to have deficiency of all blood lymphocyte populations, but other hemopoietic lineages appeared to be normal. In addit ion, his fresh T cells were principally CD45RA(+), CD62L(+), and deficient in the Fas receptor. This deficiency of all blood lymphocyte populations ma y be due to an overdose of a gene or genes located in the region of chromos ome 4 or a partial deficiency of a gene or genes in the region of chromosom e 13 that regulate the development of the lymphocyte lineage. Since the mot her contributed two copies of chromosomal region 4pter-q12 and no copy of 1 3pter-q12, the deficiency of all blood lymphocyte populations in our patien t may be the result of either uniparental disomy or imprinting. A maternal granduncle with dissimilar dysmorphic features was not lymphopenic but was neutropenic, (C) 2001 Wiley-Liss, Inc.