Abnormal centromere-chromatid apposition (Acca) and Peters’ anomaly

Peters anomaly in a red kangaroo (Macropus rufus)

A 10-mo-old female red kangaroo (Macropus rufus) presented with a unilateral congenital corneal opacity OD. Complete ophthalmic examination revealed a shallow anterior chamber and a focal area of corneal edema with multiple persistent pupillary membranes extending from the iris colarette to the corneal endothelium adjacent to the edematous area of cornea. High-resolution B-scan ultrasound of the anterior segment showed an area consistent with thinning of Descemet's membrane in the area of corneal edema. Ophthalmic examination and ultrasound findings are consistent with a diagnosis of Peters anomaly, a form of anterior segment dysgenesis. An electroretinogram performed on the affected animal did not reveal any specific abnormalities. Karyotype analyses revealed a normal diploid number (2n = 20, -XX), with an abnormal pericentric inversion in the second largest chromosomal pair. The kangaroo exhibits mild compensated vision deficits in the affected eye. The maternal and paternal adult pairing has been discontinued in an effort to prevent future offspring anomalies.

Peters' anomaly: a clinicopathologic study

Two infants were born with bilateral Peters' anomaly. The first baby was a girl, born prematurely at 35 weeks of gestation and who died 8 days later. The second infant was a boy, born at 38 weeks of gestation, who had severe conotruncal abnormality of the heart. Both babies had distinctive facial dysmorphism and severe central nervous system abnormalities including partial or complete absence of the corpus callosum and cerebral calcifications. Biochemical and genetic investigations showed no abnormalities in either child and there was no family history of genetic disorders. Neither case showed evidence of an intrauterine infection. Postmortem ocular findings in the first infant included bilateral herniation of the ruptured cataractous lens into the posterior corneal defect, iridocorneal adhesions, persistent hyperplastic primary vitreous, and total retinal detachment. The left eye of the second infant was eviscerated at 11 months of age because of recurrent, spontaneous perforation. Pathologic ocular findings included large fragments of lens material adherent to the posterior corneal stroma through a large central defect in Descemet's membrane and endothelium, fibrovascular proliferation of the adjacent corneal stroma, and iridocorneal adhesions.

Studies of mitotic and centromeric abnormalities in Roberts syndrome: implications for a defect in the mitotic mechanism

Roberts syndrome is an inherited human condition that is of particular interest because separation of centromeres and constitutive heterochromatin is observed in metaphase chromosomes. In this study we investigated the frequency of other cytological abnormalities in three Roberts syndrome patients. Our findings when taken with previous cytological reports emphasize that there are other features that are equally characteristic of Roberts syndrome: (1) aneuploidy with random chromosome loss and (2) micronuclei and/or nuclear lobulations of 8%-24% of interphase cells. We observed abnormal chromosome movement involving one or all the chromosomes during anaphase. Evidence is presented suggesting that aneuploidy, micronuclei and abnormal nuclear morphology are a direct result of lagging chromosomes. The cytological features documented for Roberts syndrome indicate that this is a human mitotic mutant.

Incidental detection of premature centromere separation in amniocytes associated with a mild form of Roberts syndrome

Premature centromere separation (PCS) was detected in amniocytes after an amniocentesis was done because of markedly elevated maternal serum alpha-fetoprotein values in a healthy primiparous young woman. PCS has been associated with the Roberts-SC phocomelia syndrome (RS). By 23 weeks' gestation, ultrasonic evaluations did not reveal abnormal fetal development. The pregnancy continued and a male infant was born with mild manifestations of RS. PCS was confirmed in cord blood lymphocytes. This case illustrates that PCS, when detected in amniotic fluid cell cultures, requires a thorough evaluation.