September 25, 2022

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Scientific Reports: Finger length can predict the severity of  COVID-19?

Scientific Reports: Finger length can predict the severity of  COVID-19?


Scientific Reports: Finger length can predict the severity of  COVID-19?

Since the outbreak of the COVID-19 epidemic, it has continued to evolve. The infectivity of different strains, the severity of infection, and the clinical outcome are all issues of great concern to people. Relevant biological marker studies are also emerging in an endless stream. However, these markers have a wide variety of types, high levels of unknowns, and complex mechanisms. In different studies in different countries, there are differences in the predictors of mortality and mortality.


For example, data from Belgium suggest that post-COVID-19 severity is associated with advanced age, renal insufficiency, elevated lactate dehydrogenase, thrombocytopenia, and obesity. 


The severity of Covid-19 infection in many populations is related to gender: men are more severe than women, and men have higher mortality rates. There are two main theories for this phenomenon:

(1) the androgen drive theory;

(2) the male hypogonadism theory.

Hormone-related disease severity differences are behind both theories, so can sex hormone-related indicators be used as predictors of COVID-19 severity?


In March of this year, the journal Scientific Reports recently published a study. Scientists studied the length ratio of the four fingers (index finger, middle finger, ring finger, and little finger) except for the thumb of COVID-19-infected and healthy subjects, and explored its relationship with Association of severity after infection with Covid-19. The study found that shorter ring finger length in men is a sign of lower testosterone, and the androgen testosterone is associated with post-COVID-19 severity, so finger-length ratio may be a predictor of severe COVID-19 infection and an increased risk of hospitalization after infection .


Scientific Reports: Finger length can predict the severity of  COVID-19?


The following information on patients was recorded in the study protocol: disease severity (0-4 points; 0-asymptomatic, 1-mild, 2-moderate, 3-severe, 4-fatal), Length of hospital stay and oxygen therapy, ICU days, concomitant diseases, history of smoking and occupational exposure, laboratory test results (white blood cell count, fibrinogen, d-dimer, platelet count, oxygen saturation, calcitonin original) and anthropometric measurements. The control group consisted of 47 women and 53 men, and the patient group consisted of 26 women and 28 men.


Based on the correlation between finger length ratio and case fatality rates (CFR), the researchers concluded that compared with controls , patients hospitalized with COVID-19 had:
(i) higher ratio of left and right finger lengths, and higher delta left-right asymmetry, i.e. low prenatal testosterone and high prenatal estrogen exposure history;
(ii) High|(right-left)| unsigned asymmetry (FA), i.e. elevated levels of developmental instability caused by stressors such as sex steroids during puberty.


Scientific Reports: Finger length can predict the severity of  COVID-19?

Legend: index finger (2D), middle finger (3D), ring finger (4D), little finger (5D), patient (P), control (C). Average of 2D:3D, 2D:4D, 2D:5D, 3D:4D, 3D:5D, 4D:5D finger length ratio unsigned asymmetries (|right-left|). The clinical composite asymmetry (Comp-Asym) was calculated as (|right-left)|2D:4D+|right-left)|3D:5D)/2.


There may be a considerable correlation between finger length ratios. For example, 2D:4D exhibits developmental stability, while 3D:5D is particularly unstable during development.

The modes associated with 2D:4D and 3D:5D are least likely to be affected by the interrelationship between the finger length ratios.

Thus, 2D:4D may be associated with prenatal-related factors, while 3D:5D may be associated with postnatal effects of developmental instability. So 2D:4D and 2D:4D finger length ratios should be concerned.


The study also examined the role of prenatal sex steroids and postnatal developmental instability in the course of COVID-19.

The results suggest that the finger length ratio and its asymmetry can be used as simple clinical markers of the potential risk of hospitalization due to COVID-19.

For finger length ratios, the effect included all 5D finger length ratios, ie 2D:5D, 3D:5D and 4D:5D (patient > control). For directional (left-right) asymmetry, there were no significant differences between patients and controls.

The unsigned composite asymmetry of 2D:4D and 3D:5D may help identify individuals at high risk for hospitalization due to Covid-19 , the researchers said .  


Scientific Reports: Finger length can predict the severity of  COVID-19?

Legend: ROC curve of clinical compound asymmetric COVID-19 disease.


In summary, the study found differences in finger length ratios and their symmetry between patients hospitalized with COVID-19 and controls.

Compared with controls, patients had a higher level of developmental instability, and attention should be paid to those involving the little finger.

Finger length ratio. The indicator of “clinical compound asymmetry” may be useful for identifying individuals with high developmental instability, and therefore may be used to distinguish individuals with more severe infection after COVID-19 infection.

However, to validate the prognostic value of clinical recommendations related to finger length ratios, further studies based on large populations of different ethnic groups are required.









Reference source:

1. Kasielska-Trojan, A., et al. “Digit ratios and their asymmetries as risk factors of developmental instability and hospitalization for COVID-19.” Scientific Reports 12.1 (2022): 1-10.

Scientific Reports: Finger length can predict the severity of  COVID-19?

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