SOX3 deletion in mouse and human is associated with persistence of the craniopharyngeal canal.

CONTEXT: SOX3 is an early developmental transcription factor involved in pituitary development. In humans, over- and underdosage of SOX3 is associated with X-linked hypopituitarism with variable phenotypes ranging from isolated GH deficiency (GHD) to panhypopituitarism, with or without mental retardation and, in most cases, with reported pituitary imaging, an ectopic/undescended posterior pituitary. PATIENT: We present a young patient with hemophilia B and developmental delay who had a 2.31-Mb deletion on Xq27 including SOX3, F9, and eight other contiguous genes. He developed GH and gonadotropin deficiency, whilst his thyroid function was in the low normal range. Magnetic resonance imaging revealed a eutopic posterior pituitary and the unusual finding of a persistent craniopharyngeal canal that has not previously been described in patients with congenital hypopituitarism. OBJECTIVE AND METHODS: To establish whether loss of SOX3 can account for the human phenotype, we examined in detail the hypothalamo-pituitary region of neonatal Sox3 null mice. RESULTS: Consistent with the patient's phenotype, Sox3 null mice exhibit a ventral extension of the anterior pituitary that penetrates, and generates a mass beneath, the sphenoid bone. This suggests that the defect results from abnormal induction of Rathke's pouch, leading to a persistent connection between Rathke's pouch and the oral ectoderm. CONCLUSIONS: Our observations expand the spectrum of phenotypes observed in association with altered SOX3 dosage and may affect the approach to genetic screening. Screening for SOX3 should be advised not only for hypopituitary patients with an ectopic posterior pituitary, but also for those with a structurally normal pituitary and additional findings, including clefts and a persistent craniopharyngeal canal, with or without mental retardation.

A novel dysfunctional protein C (protein C Padua 2) associated with a thrombotic tendency: substitution of Cys for Arg-1 results in a strongly reduced affinity for binding of Ca++.

A dysfunctional protein C (PC) molecule (Protein C Padua 2) was found in a 40-year-old man presenting with recurrent deep vein thrombosis/pulmonary embolism and a family history of thrombotic disease. The patient exhibited a normal PC antigen level, normal chromogenic activity (using Protac as PC activator) but markedly reduced coagulometric activity. After adsorption of patient plasma onto Al(OH)3, between 30% and 45% PC antigen/chromogenic activity but no coagulometric activity was detectable in the supernatant. The dysfunctional molecule exhibited reduced affinity for a Ca++ dependent anti-protein C monoclonal antibody as detected by specific ELISA assay. Immunoblotting experiments showed that PC Padua 2 had an increased MW (95 kD v 65 kD for normal PC). The lesion responsible was determined by PCR/direct sequencing to be a heterozygous CGT/TGT transition in exon 3 of the protein C gene resulting in the substitution of Arg by Cys at residue--1 in the pro-peptide leader sequence. The presence of a high MW PC was consistent with the fact that (part of) the propeptide (at least Cys-1) still was attached to the protein C molecule. This finding could also explain the strongly reduced affinity of PC Padua 2 for the Ca++ dependent anti-protein C monoclonals.

A Gla domain mutation (Arg 15-->Trp) in the protein C (PROC) gene causing type 2 protein C deficiency and recurrent venous thrombosis.

A heterozygous CGG-->TGG (Arg 15-->Trp) substitution was detected in a family with inherited type II protein C deficiency and recurrent venous thrombosis. The mutation, which co-segregates with the deficiency state, occurs in a conserved pentapeptide within the gamma-carboxyglutamic acid (Gla) domain of the protein.

A novel nonsense mutation in the protein C (PROC) gene (Trp-29-->term) causing recurrent venous thrombosis.

A novel heterozygous TGG-->TAG (Trp-29-->Term) substitution was detected in three members of a family with inherited type 1 protein C deficiency and recurrent venous thrombosis.

Family studies in von Willebrand's disease by analysis of restriction fragment length polymorphisms and an intragenic variable number tandem repeat (VNTR) sequence.

We have previously identified a microsatellite variable number tandem repeat region of the nucleotide sequence ATCT within intron 40 of the von Willebrand factor (vWF) gene. By polymerase chain reaction (PCR) amplification of this region, eight major alleles have been demonstrated in the South Wales population, with an overall heterozygosity rate of 75%. Direct sequencing has shown that the alleles correspond to lengths of between six and 14 ATCT repeats. In the present study we describe the use of this variable repeat sequence and previously reported restriction fragment length polymorphisms (RFLP) to study inheritance patterns in families with type I, IIA and severe type III von Willebrand's disease (vWD). The results confirm that analysis of this precisely localized intragenic locus provides a highly informative marker for gene tracking studies in the major forms of vWD.

Family studies and prenatal diagnosis in severe von Willebrand disease by polymerase chain reaction amplification of a variable number tandem repeat region of the von Willebrand factor gene.

We have previously demonstrated within intron 40 of the von Willebrand factor (vWF) gene a region of ATCT repeats that was shown to vary in length between two different DNA clones from unrelated individuals. The polymerase chain reaction (PCR) was used to examine the variability in length of this variable number tandem repeat (VNTR) in 53 normal individuals, using primers to DNA sequence flanking the repeat region. Overall, eight different length allelic bands were seen. These were individually sequenced and shown to contain from 6 to 14 ATCT repeats (a nine-repeat band was not seen). Seventy-five percent of individuals were shown to be heterozygous for this vWF.VNTR, and family studies showed Mendelian inheritance with allelic frequencies from 1% (vWF.VNTR [8] and vWF.VNTR [14]) to 39% (vWF.VNTR [7]). In the family of a patient with type III severe von Willebrand disease (vWD), vWF.VNTR results mirrored the phenotypic data and results with previously reported intragenic vWF restriction fragment length polymorphisms (RFLP). The patient was shown to be a compound heterozygote. In a family with a child with severe type III vWD, prenatal diagnosis by vWF.VNTR analysis on DNA obtained by chorionic villus sampling at 10 weeks gestation during a subsequent pregnancy indicated a severely affected fetus. This diagnosis was confirmed by fetal blood sampling at 18 weeks.