Tracing the haemophilia gene
How the gene was traced
The genetic laws governing how haemophilia is passed on are very clear: if a haemophilic man has children, none of his sons is affected in any way, but all his daughters are carriers (so do not have the condition themselves, but can pass it on to their sons). If a woman is a carrier then each of her children has a 50% chance of being a haemophiliac or a carrier (depending on whether they are a boy or girl). Large Victorian families tend to show this up very well. These rules mean that the surnames in the gene tree change at least every other generation which is never an ideal situation for a genealogist; and a further complication is that approximately 25% of cases of haemophilia are spontaneous, so looking for occurrences in earlier generations is a waste of time.
When tracing back, every time I was faced with a haemophiliac on the tree, either he was the first with the condition (25%) or his mother was a carrier (75%). Every time I was faced with a carrier there were three possibilities: she may be the spontaneous case (25%), her father may have been a haemophiliac (50%) or her mother may have been a carrier (25%). It was theoretically possible, therefore, to trace back several generations with no apparent haemophiliacs and not know whether you had come across a long sequence of carriers or whether you had already passed the source. None of these early cases would, of course, use the term haemophilia and before 1837 it was very unusual for the cause of death to be listed. To prove someone had the condition, therefore, required tracing down through the tree from a suspected haemophiliac or carrier until a post-1837 certificate gave an appropriate cause of death.
We know, for certain, that Isabella Smart (nee Hutson) was a carrier, as at least two of her sons died from haemorrhages. Her eldest child, Henry, was only two when he died; but we have no record of the cause of death. However, we do know about two other sons: John died from a fourteen day intestinal and stomach haemorrhage and Alfred after a twenty hour intestinal haemorrhage. Alfred was twenty-five when he died and his only child was only a few months old, but John was fifty-two. To have lived long enough to have children (or, in John's case into his fifties) suggests that the haemophilia was not the severest type. In fact we know from recent sufferers that it is only a moderate form of the condition, which is good in that those with the condition have been able to leave descendants; but it does mean that the age of death is not always a good clue as to whether someone was a haemophiliac. Alfred's death certificate has 'eight years' next to 'intestinal haemorrhage' , but it has been crossed out and replaced with '20 days'. This could mean that Alfred had been suffering from haemorrhages for eight years before the last one killed him, although it would be surprising if the symptoms had not shown in his childhood.
Did Isabella inherit the condition from her father, John, or mother, Harriet (nee Heathorn)? Her father died when he was sixty having worked as a baker all his life, so seems an unlikely candidate and her mother's name was was the much rarer Heathorn, so the search focused on her. Of her three brothers, Brian was a hatter who died of phthisis (tuberculosis) which proves nothing; and, while another brother, Thomas, died of an aneurism (which could have been related to haemophilia), he was a carpenter, which seems an odd occupation for someone trying to avoid cuts! By 1871 he had become a coffee house keeper, but both his daughters died unmarried, so we can learn nothing more. However, the third brother, John, was interesting. In 1841 he was living with an older widow and her children while working as a baker. Six years later he married this landlady and in 1851 he was listed as a 'laundress' (sic), although this may be a mistake as that had been his wife's occupation ten years earlier. Unusually his 15 year-old niece was living with him as a servant. Was she acting as an unpaid nurse? In 1861 he was a baker's assistant, apparently a demotion from his earlier existence and, by 1871, he was living separately from his wife, although both he and his wife were described as married. John was now a shirt dresser and was being looked after by a housekeeper. By 1878 John had moved to the City Road workhouse and, when his wife died in 1880, her will did not refer to John except after it had been proved when there is a sentence saying that she had 'survived her husband John Hutson..' and another referring to 'a certain agreement dated 15th day of August 1870' enabling her to dispose of her assets. John survived her by ten years, dying as a pauper in the workhouse where he had been living for twelve years. The 1881 census had described him as a baker, which he hadn't been for some time and there is no reference to any haemorrhages at any stage; but it is difficult not to believe that he was, given the unusual life he had led.
Although not proven, at this stage I had to assume that his mother was a carrier. She, Harriet, was the elder daughter of Thomas and Mary Heathorn. Thomas died when he was only thirty, so very much a possible haemophiliac. In the list of Surrey voters entitled to sit on juries, written on 4th Oct 1785, his entry has 'infirm' next to it; he wrote his will on 22nd Nov 1785; and was buried on the 4th Dec 1785. Apart from one instance where he was described as a yeoman, every other reference to him says he was a gardener. His will and land tax records showed that he owned land, and his father had also been a yeoman, so he was comfortably well off. There are, of course, a number of reasons why a thirty year-old could die, but it is reasonable to assume he might be haemophiliac. The easiest way tp prove it would be to show that two or more of his children had the condition, but he only had two daughters (mentioned in the will), the second one being Mary. The West Clandon burial registers show two Mary Heathorns being buried in 1790 and 1794. The one in 1794 is Thomas' mother and we know Thomas' widow re-married in 1794, so the 1790 entry could refer to Thomas' daughter. She would only have been seven or eight at the time, so normally the entry would refer to her parents; but I can find no other burial or marriage reference, except one in Devon 
Interesting ancestors of Isabella who may be haemophiliacs
- A Mary Heathorn did marry an Andrew Battishill (indexed as Ballyshill) in Devon in 1805 and the couple did later move to Stepney, close to where Mary's 'sister' was living. I have fund baptismal entries for daughters in Cornwall, Devon and (many years later) Stepney. There is also a burial entry for the youngest daughter but I haven't found any for the elder two. Possible marriages and children from those marriages have been followed up to no avail. Twenty years after Andrew and Mary Battershill were first sighted a document showed up throwing more light on the family. It is an examination of Andrew Battishill by the overseers of Stepney, a few months before he died. It confirms that the couple had been in Cornwall and Devon before coming to Stepney and that Mary had been given £3 by the overseers of Spreyton in Devon, Andrew's birthplace, after Andrew had become ill in Cornwall and couldn't work as a carpenter. Importantly it names only one child: William, aged about eight. The older two daughters had either died or were no longer dependant on their family. A William Batishill died in 1838 aged 24, but unfortunately the cause of death is dyspnea (shortness of breath) rather than a haemorrhage. William died in the London Hospital, so it's just possible that he went there suffering from the consequences of bleeds and a haematoma caused the dyspnea; but there is no mention of this so it seems unlikely.