The kindred¶
In genetics, a kindred is an extended family traced through a shared inherited variant. This one is unusual: a living pedigree spanning five generations, all connected by the same single-copy SAMHD1 p.A565T variant. That reach across the lifespan makes it a rare natural-history "time machine" — it lets us see, in one family, what the variant does at three months old, in mid-life, and potentially into the tenth decade.
Privacy
No names, ages, dates, or identifying details of family members appear on this site. The kindred is described only by generation, relationship, and de-identified phenotype. Detailed clinical records are held privately and are never published.
The pedigree, de-identified¶
| Generation | Carrier status | De-identified phenotype |
|---|---|---|
| G1 (eldest) | Presumed | Survival into advanced old age — the most time-sensitive natural-history data point in the family. Either the variant is survivable to great age with variable expression, or a full "crash" requires an environmental trigger this individual avoided. |
| G2 | Confirmed | Post-viral fatigue syndrome (ME/CFS) diagnosed decades ago — the earliest confirmed ME/CFS in the pedigree. |
| G3 | Confirmed (multiple) | A range spanning affected and subclinically unaffected carriers. One clinically unaffected adult carrier is scientifically pivotal — a possible model of downstream suppression rather than absence of the variant. |
| G4 | Confirmed / presumed | Index generation. Adult-onset multi-system disease in one member; in a child, exercise intolerance in pre-adolescence progressing to full ME/CFS after a viral infection. |
| G5 (youngest) | Presumed | An infant — the highest clinical-urgency member; pediatric interferon surveillance proposed. |
Patterns that make this family informative¶
Anticipation — decreasing age of onset across generations. Later generations appear to develop symptoms earlier than their forebears. One candidate explanation is accumulating genomic instability from SAMHD1's DNA-repair role, with each generation inheriting a heavier replication-error burden. (Hypothesis — not established.)
A built-in "control" carrier. A clinically unaffected adult carrier in G3 is arguably the most valuable data point in the whole study. If we can determine why that individual is protected — an independent suppressor of the same downstream pathway, compensation by the healthy gene copy, or a simple dosage threshold — we learn where the system's tipping point actually is. Their baseline interferon readouts are expected to be the most interpretively rich measurements in the project.
Transmission that looks higher than chance. Across tested members, the variant appears to be inherited more often than the 50% a single-copy variant predicts. The proposed explanation is post-meiotic selection — a survival advantage for gametes or early embryos carrying the variant, possibly via the same heightened antiviral/implantation biology. This is explicitly not meiotic drive, and it remains a hypothesis requiring formal cascade testing before it can be stated as fact.
A pregnancy paradox. The same chronically elevated interferon tone may help early in pregnancy (supporting implantation) but harm late in pregnancy (a pattern of pre-eclampsia and early delivery recurring across generations). That duality is itself in-vivo evidence of an elevated baseline immune tone throughout the kindred — and a caution that any interferon-suppressing therapy would need careful timing in anyone who might become pregnant.
Why a family study, not just a case report¶
A single patient can show what is wrong. A five-generation kindred can show how the variant behaves over a lifetime — onset, progression, protective factors, and reproductive effects — with the shared genetic background acting as its own comparison group. That is what turns one person's diagnosis into generalizable science, and it is the backbone of the project's objectives.