Biomedical subjects
Publications and source records attributed to S Baldinger.
Apert Syndrome is characterized by craniosynostosis, bilateral syndactyly, and midfacial hypoplasia. Although it was first described by Wheaton in 1894, it was first diagnosed prenatally only a decade ago-with only five cases reported in the literature. A sixth case is reported here. Prenatal diagnosis of Apert syndrome is reviewed.
Theoretically, every pericentric inversion can give rise, during meiosis, to 2 alternate recombinant chromosomes. One of these will have a duplication of short arm material and deletion of long arm material (dup p), and the other, a duplication of a long arm material and deletion of short arm material (dup q). However, most published cases have been limited to a single recombinant type occurring within a given kindred. Here we document a large pericentric inversion of chromosome 4 which gave rise, within 2 generations of a kindred, to both dup p and dup q recombinants. The family was ascertained by the birth of a baby girl with multiple congenital anomalies suggestive of Wolf-Hirschhorn syndrome, and was found to have a dup 4q recombinant. Subsequent studies of her father and of her 27-year-old mentally retarded aunt showed a balanced inv(4) (p15.32q35) and a dup 4p recombinant, respectively. Given that: (a) the balanced inversion involves approximately 87% of the length of chromosome 4; (b) the predicted meiotic pairing would be homosynapsis with loop formation; (c) the size of the segments distal to the breakpoints of the inversion are of similar and relatively small size; and (d) both recombinants are compatible with life, then the risk for recurrence of a recombinant in this family is high. Genetic counseling addressed these issues, and to date, both chronic villus sampling (CVS) and amniocentesis have been provided for prenatal diagnosis.
Autosomal dominant polycystic kidney disease presenting in the fetus or newborn is rare, only 22 cases having been reported in the literature. A case is reported of a premature newborn infant with severe renal involvement and extrarenal associated abnormalities. The literature is reviewed, and the importance of considering this entity in infants with polycystic kidney disease is discussed since it may affect both genetic counseling and surgical management when radiographically detected.
An additional case of amniotic fluid trisomy 20 mosaicism is presented. After careful counselling, the pregnancy continued and a phenotypically normal female was delivered. This case of amniocyte mosaicism establishes the source of aneuploid cell line as amnion. Since an extra-embryonic origin of the mosaicism has been confirmed, this should be carefully considered as a real possibility in counselling such families.
Arylsulfatase A (ASA) deficiency is the cause of early and late onset metachromatic leukodystrophy (MLD). Low ASA levels are detected in some healthy individuals who are pseudodeficient (PD). PD individuals can be distinguished, because PD fibroblasts hydrolyze 14C-sulfatide at similar rates to normal fibroblasts. This has also been demonstrated in amniocytes and chorionic villi (CV). The genetic basis for PD is not clearly understood and is most likely heterogeneous with respect to allelic mutations of the ASA gene. It is hypothesized that the PD phenotype can either be due to PD/PD or PD/MLD genotypes, only the latter representing a potential risk to offspring. We report an unusual family where two siblings, both carriers of the classic late infantile MLD allele, are married to unrelated PD individuals. One couple has two PD offspring; their "at risk" status, due to the lack of an affected offspring is in question. The other couple terminated a fetus determined to be affected with a "MLD variant", most likely a compound heterozygote. Cautions prenatal counseling of PD families is essential. The population frequency of the PD phenotype is unknown.
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