Sirenomelia (Mermaid Syndrome): An Infant from Parents Who Used a Special Form of Snuff
H.R. Jafari Naveh,
F. Morteza Zade
We report the first case of a fetus with sirenomelia or mermaid syndrome, whose Afghanian parents were heavy user of a special form of snuff. The case was diagnosed as a mermaid syndrome but some of the features were common to both symmelia dipus and symmelia apus, for example, the single lower extremity had the normal femur, tibia and fibula, but the single foot was rotated medially. The digestive tube ended to a massive closed saclike structure and the anus was absence. The external genital organs were rudiment and the normal testes were undescended. Aorta was divided to branches, such that the external iliac arteries were very small in comparison to the internal iliac arteries. Inferior Vena cava was placed on to the left side of the aorta and unlike the majority of reported mermaid syndrome, the bladder was present. So, the researchers believe that the present case is a rare variant of the mermaid syndrome.
Sirenomelia or the mermaid syndrome is a rare congenital malformation involving
multiple organs. It is characterized by the fusion of the lower extremities
(Lutz et al., 2004). There are some anomalies
which accompany this syndrome like: imperforate anus, renal agenesis, absent
bladder, sacral agenesis, colonic atresia, rectal atresia and absent internal
genitalia. Usually, the gonads are present but remain ectopic in position like
the abdominal cavity or the inguinal canal. The incidence of the sirenomelia
has been reported as 0.8 in 100,000 (Stanton et al.,
2003), to 1.5- 4.2 in 100,000 (Horikoshi et al.,
2005). The condition occurs predominantly in males, with a sex ratio of
2.7: 1 (Murphy et al., 1992). Most of the cases
of the syndrome are stillborn, or die during or shortly after birth. Until 2005,
only four cases of a surviving infant with sirenomelia have been reported by
Horikoshi et al. (2005).
Use of different forms of oral tobacco is dramatically increasing in the world,
but the users are not aware of the health its health risks of some special forms
(Soldz et al., 2003; Vander
Weg et al., 2008; Zatterstrom et al.,
2004). In addition, health effects of the special form snuff which used
commonly in east South region of Iran and Afghanistan are not completely studied.
Our report shows that use of this form snuff by parents may cause severe malformations
in the developing fetus. It is suggested that more studies to evaluate the teratological
effects of intake of the special form of snuff need to be elaborated.
A rare variant of Sirenomalia, Mermaid syndrome was obtained from the Niknafs Maternity Hospital of Rafsanjan City, who had died just after delivery. His parents were Afghanian in origin. His parents were heavy user of a special form of snuff (an oral form of tobacco product).
Examination of the perineal region and the lower limb exhibited malformations.
The fetus had one medially rotated limb. Small rudimentary penis with no scrotal
sac was seen (Fig. 1A).
The anus was absence (Fig. 1B). In the sacral region, there
was an obvious spine deformity. Upon dissection, the following features were
observed, the normal testes which had not descended, lying within the abdominal
cavity at the deep inguinal ring.; the large intestine ended in a massive closed
saclike in the left iliac region (Fig. 2A). The caecum and
vermiform appendix lay in the left inguinal region. The abdominal aorta was
divided into two common iliac arteries but on the both sides there were small
external iliac arteries and large internal iliac artery. Abdominal aorta was
situated left to the inferior vena cava (Fig. 2B).
||(A, B) Anterior and posterior views of the case. Note to the
single lower extremity with malrotated foot, the external genital organs
with only a small rudimentary penis, the narrow radix of the first right
finger (pollex) in the anterior view and absence of anus in the posterior
||Photographies of the dissected case. (A) Photograph of whole
dissected abdominal cavity. The large liver, the massive closed saclike
end of digestive tube and the testis are shown with star, white and black
arrow, respectively and (B) photograph of the abdominal aorta and its main
branches. Note to the small external artery and inferior vena cava on the
left side of the abdominal aorta. 1: Abdominal aorta, 2: Common iliac artery,
3: Internal iliac artery, 4: External iliac artery, 5: Inferior vena cava
||Radiographs from the case. (A) X-ray from the single lower
extremity showing normal size of tibia and fibula and (B) X-ray showing
additional ribs in both sides and normal size of tibia bone. With regard
to the single lower extremity and finform malrotated foot our case is classified
to the symmelia apus and symmelia dipus groups, respectively. The first
and thirteenth ribs are shown with arrow
Both the lobes of the liver occupied the upper abdominal cavity with a gall
bladder. The urinary bladder was present (Fig. 2A). The radiographs
showed that the femur, the tibia and the fibula of the single lower limb were
normal. The femur bone articulated with the left acetabulum (Fig.
3A). He had 13 ribs on the both sides (Fig. 3B). The first
right finger (pollex) was abducted and was narrow in the radix (Fig.
The first reported case of the mermaid syndrome was in the 16 century (Lutz
et al., 2004). One of oldest studies was done by Malinger
et al. (1987). Sarpong and Headings (1992)
classified the syndrome into 3 groups according to the number of feet present.
The first group is called symmelia apus, in which both legs are merged completely
into a single lower extremity, with both the feet absent or rudimentary. The
second group is symmelia unipus; Fetuses have 1 foot, 2 femora, tibiae and fibulae.
In the third group that is called symmelia dipus, 2 distinct feet are present
but are malrotated and resemble fins (Sarpong and Headings,
1992). This case belongs to the symmelia apus variant having one foot with
1 femur, tibia and fibula (Fig. 1A). The last feature (i.e.,
his foot rotated medially and was resemble fin) can set our case symmelia dipus,
but unlike the majority of previous reported cases, the fibula and tibia in
the single lower extremity is normal in size and form (Fig. 3).
Although, some features were similar to fetus in unipus group, for example fetuses
in the third group have two distinct feet but our case had only one finform
Several etiological factors have been suggested as to the pathogenesis the
syndrome such as: caudal somite destruction, cloacal malformation and neural
tube distention. Duhamel suggested that a deficit in the formation of the caudal
region prior to the 4th week of gestation leads to this malformation. Duhamel
suggestion has led to the commonly used term, \caudal regression syndrome (Lutz
et al., 2004). Rougemont et al. (2008)
suggested that a defect in the blastogenesis leads to this condition. The theory
as known, vascular steal was first proposed by Stevenson. This theory suggests
that blood is diverted by a single large artery arising high on the abdominal
aorta. However, it still remains unknown that sirenomelia is part of the spectrum
of caudal regression or a distinct entity (Duesterhoeft
et al., 2007). Relative ischemia to the caudal part of the developing
embryo seems to be evident in the present case as the divisions of the aorta
was not normal; the external iliac arteries were smaller in comparison with
the internal iliac artery. In addition the aorta was placed on the right side
of inferior vena cava (Fig. 2B).
The etiology of this malformation still remains unknown. Reports have shown
that association between the syndrome and maternal diabetes, cocaine exposure
and monochorionic twin exist (Van Zalen-Sprock et al.,
1995; Di Lorenzo et al., 1991).
Snuff is a powder tobacco product which is consumed by placing it under the
upper lip for an extended period of time (Vander Weg et
al., 2008). The parents in the present case used a form of snuff
which is manufactured in East South region of Iran and Afghanistan. It consists
of a complex of tobacco and little of lime [Ca (OH)2]. The health
effects of this form of snuff have not been completely studied, but it seems
that it causes oral and esophageal cancers. We assume that the abnormalities
in our case could be due to the use of snuff by his parents. In certain
areas of Iran and Afghanistan, usage of this form of snuff is very common but
unfortunately, very few studies about its health effects have been conducted
(Glenn et al., 2008).
At the first present results show that the presented case was a rare variant of the mermaid syndrome and he wasnt grouped in the famous classification of the syndrome. In addition, using the mentioned form of snuff by parents may cause serious malformations in their fetus. It is suggested that the consequence of snuff consumption by parents on the fetus deserve further studies.
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