Morquio syndrome (MPS IVA) and hypophosphatasia in a Hutterite kindred

Fetal presentation of Morquio disease type A

A fetus with mucopolysaccharidosis type IV A (Morquio type A) is described. The family had one affected child exhibiting symptoms of classical Morquio A disease, and late in the subsequent pregnancy prenatal diagnosis was requested. At 23 weeks' gestation, moderate ascites was detected by detailed ultrasound scan and keratan sulphate was found in the amniotic fluid. The pregnancy was terminated by prostaglandin induction and the diagnosis of mucopolysaccharidosis type IV A was confirmed by demonstration of a deficiency of N-acetylgalactosamine-6-sulphate (GalNac-6-S) sulphatase in cultured amniotic cells and in post-mortem fibroblast cultures. The activities of beta-galactosidase and arylsulphatase A were normal, ruling out Morquio disease type B and multiple sulphatase deficiency. These results indicate that mucopolysaccharidosis IV A (a disease that predominantly affects the skeletal system) may produce ascites in the fetus to such an extent that it can be detected by ultrasound.

Bovine beta-mannosidase deficiency

A fatal inherited glycoprotein storage disorder is described in Salers cattle which affects both sexes. Affected calves are unable to stand at birth, have a marked intention tremor, markedly enlarged kidneys, decreased white matter in all areas of the brain, and cytoplasmic vacuolation in multiple cell types of multiple tissues with nervous, renal, lymphoid and thyroid tissues most severely affected. Affected calves were grossly deficient in lymphocyte and brain beta-mannosidase activity and had markedly reduced but not deficient activity in liver and kidney. A test mating of obligate carriers produced three genotypes: affected, carrier, non-carrier in essentially the expected ratio of 1:2:1, consistent with autosomal recessive inheritance.

Recursive descent probabilities for rare recessive lethals

Recursively computed descent probabilities provide an effective way to evaluate possible ancestries of rare alleles segregating in large and complex genealogies, but they ignore information other than the descent to a small set of current gene copies. We show how descent probability computations can be modified to incorporate the fact that no ancestor can be affected by a lethal recessive trait. This methodology is applied to two rare recessive traits segregating in a complex Hutterite (Lehrerleut) genealogy.

Applying expert system techniques to human genetics

Although expert systems have been developed in a variety of medical areas, there has been very little application of expert system techniques to the field of human genetics. The purpose of the research project described in this paper was (1) to experiment with different types of knowledge representation for data and knowledge structures in human genetics and (2) to explore the applicability of different inference mechanisms for various genetic problems. We present an object-oriented and a fact-based model for the representation of genealogical information and describe two prototype systems.

Interleukin-2-dependent T lymphocytes for the diagnosis and investigation of inherited metabolic disorders

Interleukin-2-dependent T cell lines can be started from as little as 1 ml of peripheral blood and expanded to 50 x 10(6) cells within 12 days. These cells represent an easily obtainable source of nucleated tissue with certain advantages over skin fibroblasts or transformed B lymphoblastoid cells for the rapid diagnosis and study of inherited metabolic disorders. A panel of 19 enzymes were assayed in IL-2-dependent T lymphocytes and the diagnosis of four enzyme deficiencies is demonstrated using T lymphocytes.