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Det er fra en av avhandlingene til forsker Nikki ang Dermoid Sinus. Blir litt å tenke på etter å ha lest det et par ganger.....
INTRODUCTION
Dermoid sinus is a congenital malformation caused by an incomplete separation of the skin and neural tube during embryonic
development (Fatone and others 1995, Booth 1998, Cornegliani and others 2001).
A dermoid sinus connected to the skin can be detected by palpation. If the sinus tube develops a secondary infection, the
dog may show signs of pain during palpation.
Dermoid sinus occurrence has been reported in American cocker spaniels (Bailey and others 2001), boerboels (Penrith and van Shouwenburg 1994), boxers (Selcer and others 1984), chow-chows (Booth 1998),
English cocker spaniels (Pratt and others 2000), golden retrievers (Cornegliani and others 2001), Rhodesian ridgebacks
(Hofmeyr 1963, Hathcock and others 1979, Gammie 1986), Rhodesian ridgeback crosses (Lambrechts 1996), shih tzus (Selcer
and others 1984), Siberian huskies (Cornegliani and Ghibaudo 1999) and
Yorkshire terriers (Fatone and others 1995).
OBJECTIVES: To define the mode of inheritance of dermoid sinus.
METHODS: A chi-squared analysis was performed on data from
46 litters produced between 1990 and 2001. Data were
corrected to avoid bias in the segregation ratio.
RESULTS: In data from 57 litters (n=492), 82 dermoid sinus positive
offspring were observed. The frequency of affected offspring in the
Swedish Rhodesian ridgeback population is estimated to be
between 8 and 10 per cent.
CLINICAL SIGNIFICANCE: Bias in heredity pattern may be caused by
undetected dermoid sinus type V. Improved clinical diagnosis of
all dermoid sinus types is therefore crucial.
Inheritance of dermoid sinus in the
Rhodesian ridgeback
The first statistical trial to determine the inheritance of dermoid sinus was performed by Hare in 1932. In that study, all data were retrieved from only two sires and three dams. They produced 47 offspring.
One of the sires was dermoid sinus positive. The dermoid sinus negative sire gave rise to a total of 41 offspring, and five were
identified as dermoid sinus positive. The dermoid sinus affected sire gave rise to a total of six offspring, and two were dermoid
sinus positive. Hare presented no opinion on the statistical results.
The data by Hare (1932) were re-evaluated by Mann and Stratton in 1966. They concluded that the mode of inheritance was of a simple recessive character. Stratton collected data from breeders relating to 17
sires and 21 dams. One dam was dermoid sinus positive. The matings resulted in 48 litters with a total of 376 offspring. When
an analysis was performed using only the litters in which dermoid sinus had been detected (20 litters), the expected number of dermoid sinus positive offspring was 45. The actual outcome was 42 dermoid sinus
positive offspring. This analysis supports the hypothesis of a simple autosomal recessive trait (Swenson 1989).