237

We

can

only speculate about the origin of the air: during in-situ

hypothermic perfusion or during subsequent workbench procedures, leaking perfusion catheters may have forced air into portal vein or hepatic artery branches. The air in the hepatic veins during donor hepatectomy after in-situ suprahepatic and infrahepatic caval veins are

may have been introduced

perfusion,

when the

cut and regurgitation of air into the vessels occurs. Since no venous air embolism was observed during transplantation, the clamping and unclamping procedures during revascularisation were adequate in preventing entry of air into the recipient circulation. The effects of the air collections in hepatic artery and portal vein branches on post-transplant organ function were not clear. The two recipients with donor livers containing large amounts of air did not show signs

of major organ dysfunction. The consequences of air emboli in preservation procedures can be serious. Air emboli can impede proper perfusion with preservation solution resulting in donor organ wastage. Our fmdings may not be limited to donor livers, but may also occur in

donor hearts and kidneys. Liver Transplant Group, Departments of Radiology and

Surgery, University Hospital, RB 9700 Groningen, Netherlands

R F. E. WOLF E. L. MOOYAART M. J. H. SLOOFF

1.

Prager MC, Gregory GA, Ascher NL, Roberts JP. Massive venous air embolism during orthotopic liver transplantation. Anesthesiology 1990; 72: 198-200. 2. Khoury GF, Mann ME, Porot MJ, Abbdul-Rasool IH, Busuttil RW Air embolism associated with

veno-venous bypass during orthotopic liver transplantation. Anaesthesiology 1987; 67: 848-51.

Factor XII

deficiency and central

retinal vein

with the non-ischaemic type of CRVO. Both patients were given the non-ischaemic type later converted to the ischaemic form with permanent, severe visual impairment. In view of these findings, we suggest that patients with CRVO, especially young people, should not only have a general examination (including standard coagulation tests) but also a haemostatic work-up for rare thrombotic risks, including coagulation factor assays to detect a possible factor XII deficiency. In such cases, anticoagulant therapy should be considered to prevent further thrombotic episodes. one

anticoagulant therapy. The patient with discontinued therapy and two months

Department of Ophthalmology, University of Innsbruck, A-6020 Innsbruck, Austria; and Department of Internal Medicine, University of Innsbruck

1. Dyerberg J, Stofferson E. Recurrent thrombosis m a patient with factor XII deficiency. Acta Haematol 1980; 63: 278-82. 2. Ratnoff OD, Busse RJ, Sheon RP. The demise of John Hageman. N Engl J Med 1968; 279: 760-61. 3. Hoak JC, Swanson LW, Warner ED, et al. Myocardial infarction associated with severe factor XII deficiency. Lancet 1966; ii: 884-86. 4. Hellstern P, Kohler M, Schmengler K, Doenecke P, Wenzel E. Arterial and venous thrombosis and normal response to streptokinase treatment ina young patient with severe Hageman factor deficiency. Acta Haematol 1983; 69: 123-26. 5. Hayreh SS. Classification of central retinal vein occlusion. Ophthalmology 1983; 90: 458-74. 6. Trope G, Lowe GDO, McArdle BM, et al. Abnormal blood viscosity and haemostasis in long-standing retinal vein occlusion. Br J Ophthalmol 1983; 67: 137-42. 7. Pelosse B, Massin P, Bouzas E. Hémostase et occlusion de la veine centrale de la rétrine. Ophthalmologie 1988; 2: 335-36.

Prenatal

not only initiates the intrinsic pathway of but also coagulation, plays an important part in fibrinolytic activation. Individuals with factor XII deficiency rarely have a bleeding tendency, but they may have thromboembolic events despite prolonged activated partial thromboplastin time (aPTT).l Since the first report of factor XII deficiency in a patient who died of a massive pulmonary embolism after pelvic fracture,2several cases of thromboembolic complications associated with factor XII deficiency have been reported, such as myocardial infarction,33 repeated episodes of deep-vein thrombosis,l and the occurrence of both arterial and venous thromboses resulting in amputation of the leg in one patient.4 Central retinal vein occlusion (CRVO) can cause blindness. According to Hayreh’ss classification, there are two distinct forms of CRVO with very different courses and prognoses-the non-ischaemic type caused by occlusion of the central retinal vein alone, and the ischaemic type, which is always associated with pronounced capillary non-perfusion. The outlook is very poor for the ischaemic type, which can result in painful blindness needing enucleation. Conversion from the non-ischaemic to the ischaemic type is possible.s Although the precise cause of CRVO remains unclear, many systemic and local causes have been reported. The most important of these systemic causes are arteriosclerosis and arterial hypertension, whereas the most common ocular condition is open-angle glaucoma. Haemostatic disorders such as antithrombin III deficiency or protein C deficiency associated with CRVO6’ may be more important than generally appreciated, especially in young people. We report two patients who, as far as we are aware, are the first two known cases of factor XII deficiency associated with CRVO. The two patients were a 39-year-old man with an acute onset of severe visual impairment due to CRVO of ischaemic type and a 35-year-old man with a mild blurring of vision. At the initial ophthalmic investigation, the second patient presented with nonischaemic CRVO. Both subjects were in good health with no known risk factors for the development of thrombosis and no previous or family history of thromboembolism. Medical examination and laboratory results, including tests for haemostasis, were normal. Only the patient with the ischaemic type had a prolonged aPTT of 46 s (normal 23-35 s). A detailed haemostatic profile showed factor XII deficiency in both cases, the activity being 27% (normal 70%-150%) in the patient with the ischaemic type and 34% in the

diagnosis of myotonic dystrophy by direct mutation analysis

occlusion SiR,—Factor XII

LILLY SPEICHER WOLFGANG PHILIPP FRIEDL J. KUNZ

SiR,—Myotonic dystrophy is the most frequent, inherited muscular disorder among adults. The mode of inheritance is autosomal dominant and the myotonic dystrophy locus has been mapped to the ql3band of chromosome 19.1 DNA diagnosis of myotonic dystrophy is routine in our laboratory with any combination of proximal and distal variable simple sequence motif (VSSM) markers2,3that are linked within 1 cM to the disease locus. These linkage analyses are over 99% reliable, but the DNA test is only available for those families in which inheritance of the disease and the genetic markers can be studied in at least two affected individuals to assess the genetic phase of the marker alleles. Diagnosis of isolated cases is not possible in this way, nor can presymptomatic DNA diagnosis be offered to any of the individual’s relatives. Now, an expanded (CTG) trinucleotide repeat in the 3’untranslated region of a protein kinase gene family member3-9 has been identified as the mutation that causes myotonic dystrophy. The expansion, which can be several kilobase pairs in size, is detectable with either conventional Southern blots or with the polymerase chain reaction (PCR).7 This analysis enables direct detection of every carrier of the myotonic dystrophy mutation, postnatally as well as antenatally, with maximum reliability. In the antenatal centre of the University Hospital Dijkzigt, a 30-year-old woman was seen for genetic counselling during her first pregnancy. Her sister had been diagnosed with myotonic dystrophy some weeks earlier. Examination of the consultand and her parents, including electromyographic and slit-lamp studies, did not reveal any signs of myotonic dystrophy. Analysis2 with the GJ-VSSM2 marker D19S207 revealed that the

Rotterdam,

consultand had inherited the same marker alleles as the affected sister from both parents (figure). Because of her high risk of being a carrier, mutation typing of the CTG repeat was offered. For Southern blotting, DNA was extracted from blood samples, chorionic villi, and fetal brain (post termination), digested with BamHI and, after electrophoresis on 0-8% agarose gels, immobilised on nylon membranes (Gene Screen Plus). To identify the unstable fragment, the blots were screened with a 3P-labelled 14 kb BamHI clone that contained the trinucleotide repeat. The PCR assay was as described.7 The amplified product was analysed on 1% and 4% agarose gels. A Southern blot, made from the 1% gel on Gene Screen Plus, was screened with a 32P-end-labelled (CTG)1° oligonucleotide.