Clinical, Cytogenetic, and Biochemical Analyses of a Family with a t(3;13)(q26.2;p11.2): Further Delineation of 3q Duplication Syndrome

Abstract

Chromosomal abnormalities that result in genomic imbalances are a major cause of congenital and developmental anomalies. Partial duplication of chromosome 3q syndrome is a well-described condition, and the phenotypic manifestations include a characteristic facies, microcephaly, hirsutism, synophrys, broad nasal bridge, congenital heart disease, genitourinary disorders, and mental retardation. Approximately 60%-75% of cases are derived from a balanced translocation. We describe a family with a pure typical partial trisomy 3q syndrome derived from a maternal balanced translocation t(3;13)(q26.2;p11.2). As the chromosomal rearrangement involves the short arm of an acrocentric chromosome, the phenotype corresponds to a pure trisomy 3q26.2-qter syndrome. There are 4 affected individuals and several carriers among three generations. The report of this family is relevant because there are few cases of pure duplication 3q syndrome reported, and the cases described here contribute to define the phenotype associated with the syndrome. Furthermore, we confirmed that the survival until adulthood is possible. This report also identified the presence of glycosaminoglycans in urine in this family, not related to the chromosomal abnormality or the phenotype.

Figure 1

Pedigree of the family.

Figure 2

Phenotype of the four family members with the dup(3q) syndrome. (a) Frontal and (b) semilateral views of Case 1 (proband). (c) Case 2. (d) Case 3. (e) Case 4.

Figure 3

Cytogenetic analysis of blood lymphocytes. (a) Partial karyotype of the proband, the arrow shows the add(13)(q11.1). (b) GTG partial karyotype of individual II.4, the arrows show the t(3;13)(q26.2;p11.2). (c) 3q NOR positive of individual II.4 and acrocentric chromosomal aggregation. (d) FISH with WCP probe for chromosome 3 of individual II.4, arrows show der(13).