18-year-old woman with a history of syncope one month before the fatal event, having not consulted a doctor. She was sitting with her family on the bank of a river when she suddenly felt unwell, lost consciousness and fell into the water. She was immediately recovered from the water but died a few minutes later. Initially it was suspected that it could have been an accidental submersion.
The autopsy was performed with a postmortem delay of 16 hours. The corpse was an athletic female of a height of 1.65 m and weight of approximately 54.5 kg (BMI 20 kg/m2), with no external signs of violence or marfanoid habitus.
On opening the thoracic cavity, a massive left haemothorax of 3,000 cc was found due to rupture of a saccular aneurysm of the terminal portion of the aortic arch, slightly distal to the origin of the left subclavian artery. The aneurysm measured 4.2 x 4.6 cm and its markedly thinned wall was barely 1 mm thick. The rupture line measured 2 mm in length and was located in the infero-anterior region of the aneurysmal sac.

The heart weighed 200 g, the expected weight being 199 g according to Kitzman's tables. At the level of the subaortic endocardium there was a clear, slightly thickened area. Both the atrioventricular and semilunar valves were normal, as was the origin of the coronary arteries.
Histopathological examination of the aneurysm wall showed thinning of the aortic wall at the expense of rupture and loss of elastic fibres and reduction of muscle tissue which was replaced by a non-fibrillar basophilic matrix.

Given the suspicion of the existence of an atypical collagenopathy, i.e. without phenotypic expression, genetic screening for Marfan Syndrome was performed on the younger sister of the deceased - after genetic counselling at the Children's Hospital. The technique used was molecular genetic research of the FBN1 marker, which was amplified by standard PCR protocol, sequenced and quantified by electropherograms (capillary electrophoresis), analysed and compared with reference sequences. The study was negative. Other diseases were not screened due to the lack of genetic markers at that time.