Phenotypic manifestation in a child with 46,X,der(X)t(X;1)(q24;q31.1)

A de novo 1.38 Mb duplication of 1q31.1 in a boy with hemifacial microsomia, anophthalmia, anotia, macrostomia, and cleft lip and palate

We reported a 2-year-old boy with developmental delay, mild mental retardation, and severe craniofacial malformation, including facial asymmetry with hypoplasia of the left zygoma, maxilla, and mandible, and left anophthalmia and anotia. A genome-wide screen revealed a 1.38 Mb duplication on chromosome 1q31.1, which was absent in his parents and 27 healthy controls. The duplication region contains two Refseq genes, PLA2G4A and C1orf99, which have not been reported to be implicated in craniofacial malformation. Functional studies of these genes and additional clinical analysis are necessary to elucidate the pathogenesis of craniofacial malformation.

Unbalanced translocation in an adult patient with premature ovarian failure and mental retardation detected by spectral karyotyping and array-comparative genomic hybridization

BACKGROUND

There are only three cases of unbalanced translocation (X;1) reported in childhood in the literature, while no such phenotypic information is available in adults.

MATERIALS AND METHODS

To delineate the phenotype-genotype relationship of unbalanced translocation (X;1) in adulthood, we reported here a 20-year-old female with an unbalanced translocation (X;1) which was determined by spectral karyotyping, array-comparative genomic hybridization and subtelomeric fluorescence in situ hybridization (FISH).

RESULTS

The phenotype of partial trisomy 1 and partial monosomy X of the present case was much attenuated, including premature ovarian failure, mental retardation, class I obesity, mild dysmorphism and delayed secondary sexual characteristics. The breakpoints of the unbalanced translocation were accurately located at Xq28 and 1q32.1. The large amplification on Chromosome 1 q arm was found to involve 312 genes and the deletion on Chromosome X q arm also involved 141 genes. Overall, genes associated with physiological process (47 genes), cellular process (33), development (23), response to stimulus (1) and reproduction (1) were observed in the amplification on Chromosome 1 q arm. In addition, genes related to physiological process (23 genes), cellular process (13), development (6) and response to stimulus (2) were observed in the large deletion on chromosome X q arm. Late-replication studies revealed the existence of skewed X inactivation in the derivative X chromosome.

CONCLUSIONS

The phenotype of partial monosomy X and partial trisomy 1q is much attenuated in case of unbalanced translocation (X;1) in adulthood probably owing to skewed X inactivation in derivative X chromosome.

Prenatal diagnosis of partial trisomy 1q and monosomy X in a fetus with a congenital lung lesion and hydrops fetalis

We report on the prenatal diagnosis of partial trisomy 1q and monosomy X in a fetus with a congenital lung lesion and hydrops. The finding of hydrops in a fetus with a small lung lesion, congenital cystic adenomatoid malformation (CCAM) volume to head circumference ratio (CVR) 0.78, prompted cytogenetic analysis of amniotic fluid, revealing an unbalanced translocation between chromosomes X and 1 [46,X,der(X)t(X;1)(p11.2;q25 or q31)]. The incidence of chromosomal abnormalities with CCAM lesions is estimated at 1.6%. This is the first reported case of prenatally diagnosed partial trisomy 1q and monosomy X presenting as a fetal lung lesion and hydrops.

Attenuated phenotype in a child with trisomy for 1q due to unbalanced X;1 translocation [46,X,der(X),t(X;1)(q28;q32.1)]

We report a case of an X;1 translocation in a 9-month-old female infant with mild dysmorphic features and developmental delay. High-resolution chromosome analysis revealed a de novo, unbalanced translocation between chromosomes X and 1 [46,X,der(X),t(X;1)(q28;q32.1)]. Breakpoints on the derivative X and the size of the translocated segment have been defined by fluorescence in situ hybridization (FISH) with Xq and 1q specific probes. The rearrangement in this patient results in monosomy for Xq28-qter and trisomy for 1q32.1-qter. Replication studies demonstrated late replication of the derivative X in 80% of the observed cells, with the exception of 20% of the cells where X inactivation failed to spread into the translocated 1q segment. Patients with pure trisomy for the distal segment of 1q present a considerably more severe phenotype compared to that seen in our patient, including facial dysmorphisms, urogenital and cardiac anomalies. We suggest that the absence of many of the characteristic features for trisomy 1q in our patient, may reflect a mosaic pattern of inactivation of the translocated autosomal segment on the derivative X chromosome.