Hecht Scott Syndrome

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Hecht Scott syndrome (also known as fibular aplasia-tibial campomelia-oligosyndactyly syndrome) is a rare genetic disease that causes congenital limb formation. The main characterisation is the aplasia or hypoplasia of bones (mainly the fibula or tibia) of the limb. It is currently presenting in less than 1 in 1,000,000 newborns. It has been known to be more commonly present in males. It was first diagnosed in 2005 by Courtens et al. who recognised the malformations with his present case and four others that were similarly described in literature.

Signs and symptoms

Hecht Scott syndrome effects the tibia and fibula. Common physical symptoms show a short leg, the ankle and foot being short and deformed, absence of rays and bowing of the tibia. Another physical symptom is the presence of contralateral oligosyndactyly of the hand. Hecht Scott syndrome is also associated with psychosocial morbidity and mortality. Therefore, early diagnosis and treatment of this syndrome is vital. Prenatal screening can reveal whether the child will have Hecht Scott syndrome by observing skeletal abnormalities.

Genetics

WNT7A is a gene that is a member of the WNT family. The WNT family consists of structurally related genes. Mutations in WNT7A causes a range of diseases associated with limb malformations. Such diseases include Fuhrmann syndrome and Al-Awadi/Raas-Rothschild/Schinzel Phocomelia syndrome. However, in the case of Hecht Scott syndrome there seems to be no mutation in the WNT7A gene. Furthermore, there is a cluster of homeobox D genes on chromosome 2 that participates in the development of limbs. There is no evidence of mutations on these genes being the cause of Hecht Scott syndrome. There is no conclusive prognosis of mutation in genes causing Hecht Scott evidence but due to the high prevalence of this disease in males, it was suggested by Hecht and Scott that the disease has an "autosomal dominant gene with decreased penetrance or gonadal mosaicism." Evans et al. have also defined Hecht Scott syndrome as a "heterogeneous disorder with a dominant inheritance".

Hecht Scott syndrome often gets confused with Fuhrmann syndrome. However, in the case of Fuhrmann's syndrome, there is a homozygous mutation of WNT7A gene Furthermore, Fuhrmann syndrome patients present with pelvic and femur abnormalities.

Treatment

There is no prevention of Hecht Scott syndrome as there is no clear understanding of the causation of this disease. However, there are possible methods to treat this disease. This includes:

  • Uses of orthoses
  • Limb lengthening
  • Epiphysiodesis
  • Early amputations
  • Application of a prosthesis

There has been positive feedback with the use of Syme amputation.

History

Hecht Scott syndrome was first described in literature in 1981 by Jacqueline T. Hecht and Charles I. Scott, Jr. They outlined the symptoms in a male and a female. Hecht and Scott suggested that there was a genetic etiology as the same symptoms appeared in half-siblings. They further narrowed it down to an "autosomal dominant mutant gene with decreased penetrance or gonadal mosaicism in the mother".

Courtens et al. first published their findings on Fibular Aplasia Tibial Campomelia and Oligosyndactyly (FATCO) in 2005 in the American Journal of Medical Genetics. They identified a newborn male with similar symptoms as described in Hecht and Scott's journal and four other cases. The common finding amongst all five journals was fibular aplasia, tibial campomelia, and oligosyndactly. Courtens et al. then proposed to call this disease fibular-aplasia, tibial-oligosyndactly (FATCO) syndrome. It was also named as Hecht Scott syndrome due to the authors of the original paper that described the disease.

Cases

Case I (Jacqueline T. Hecht and Charles I. Scott, Jr., 1981)

A Caucasian male was born to a 16 year old woman and a 19 year old man in 1974. The couple were not married nor related. Pregnancy and birth process revealed no complications. Limb deficiencies were identified at birth:

  • Absent hands
  • Absent right foot
  • Absent left leg distal to the knee

X-ray films were lost; however, the reports revealed:

  • Bilateral absent hands distal to the radius and ulna
  • Absent right foot distal to tibia and fibula
  • Absent left leg distal to femoral epiphysis

The newborn also developed a cyanotic heart disease and died after 11 days.

Case II (Jacqueline T. Hecht and Charles I. Scott, Jr., 1981)

A 5 month old Caucasian female was born to a 21 year old female and 18 year old father. The couple were married and unrelated Unlike case I, the pregnancy was complicated with significant dependent oedema during the fifth and sixth months. During the sixth month of the pregnancy, bleeding increased significantly. Four days after birth, respiratory distress syndrome was identified but resolved. Limb abnormalities were immediately identified:

  • Absence of right hand
  • Right forearm with a soft tissue constriction
  • Left forearm with syndactyly of 2 digits
  • Bilateral anterior bowing
  • Bilateral oligodactyly of the feet

At 9 months, the infant was a well-developed infant who developed normally for her age. Family history revealed no signs of skeletal abnormality.

Case III (G. Capece, A. Fasolino, M. Della Monica, F. Lonardo, G. Scarano and G. Neri, 1994)

Healthy, unrelated parents had a prenatal screening performed which revealed a foetus with skeletal abnormalities. The pregnancy was terminated at 24 weeks after extensive counselling. Chromosomal analysis revealed normal results with no mutations. The ultrasound results revealed the following skeletal abnormalities:

  • Complete syndactyly of the fingers on the right (except the thumb)
  • Bowed tibia
  • Absence of fibula
  • Absence of fifth toe and club-foot bilaterally

Furthermore, a pathological examination and X-ray was performed and the following physical features were noticed:

  • Flat face
  • Large ears with a prominent helix
  • Fused eyelids (Ankyloblepharon)
  • Oligosyndactyly of the right hand
  • Absence of left fibula
  • Bowed tibia on the left

X-rays were performed on the parents hands, legs and feet and revealed normal results.

Case IV (J. Huber, J.B. Volpon and E.S. Ramos, 2003)

An 8-month old boy was assessed and identified to have Fuhrmann syndrome However, no genetic analysis was performed to reveal any mutations on WNT7A gene so it is assumed that this is another case of Hecht Scott syndrome. The parents were unrelated. Physical analysis revealed:

  • Polydactyly of both hands
  • The left leg was bowed
  • Clubbing of the feet with two toes on the right foot and three toes on the left foot

Radiographs of the boy revealed:

  • Polydactyly of both hands
  • Dislocation of hip
  • Bilateral aplasia of the fibulae
  • Broad, short and bowed left tibia
  • Two toes, with two phalanges and two metatarsals, on right foot
  • Three metatarsals, two triphalangeal toes and one toe with two phalanges on the right foot
  • Tarsal bones absent in both feet

Case V (J. Huber, J.B. Volpon and E.S. Ramos, 2003)

A 20 day old boy was assessed and was identified to have Fuhrmann syndrome. However, no genetic analysis was performed to reveal any mutations on WNT7A gene so it is assumed that this is another case of Hecht Scott syndrome. His mother had previously had a miscarriage. The parents were unrelated. Physical examiantion of the child revealed:

  • Retrognathia and a crease in the ear lobules
  • Four fingers on right hand
  • Both legs were bowed
  • Both feet had four toes

Radiographs demonstrated:

  • Absence of the fifth finger and metacarpals
  • Aplasia of fibula and bowed tibiae on both legs
  • Abnormal calcaneus in the feet
  • No fifth toes or fifth metatarsals

Both patients, at their followup appointment, showed normal development and growth. A chromosome analysis was performed and revealed normal results. There no cardiac anomalies.

Case VI (Winnie Courtens, Ann Jespers, Inge Harrewijn, Dirk Puylaert and Filip Vanhoenacker, 2005)

The infant was born to Moroccan parents (mother aged 24 and father aged 42) and unrelated. They had two children before this infant and were both in good health. Physical examination revealed:

  • Left hand with complete syndactyly
  • Right foot with absence of fifth ray and abnormal plantar creases
  • Anterior bowing of the right lower limb
  • Absence of right fibula, right fifth metatarsal and phalanges, anterior bowing and shortness of right tibia

Other investigations appeared to reveal normal results.

Case VII (Taichi Kitaoka, Noriyuki Namba, Ji Yoo Kim, Takuo Kubota, Kohji Miura, Yoko Miyoshi, Haruhiko Hirai, Mikihiko Kogo, and Keiichi Ozono, 2009)

A boy was born to unrelated, healthy father (aged 33) and mother (aged 32). Physical examination at birth revealed:

  • Left-sided cleft lip and cleft palate
  • Oligosyndactyly of right hand and bilateral feet
  • Bilateral anterior bowing of the limbs

Radiographs showed:

  • Angulated tibia with left fibular aplasia
  • Three metacarpal bones on right hand
  • Third distal phalange fused with fourth
  • A single toe was missing from both feet

Surgery was performed to repaired the boy's cleft lip when he was 3 months old. A follow-up visit at 10 months showed the boy to develop normally for his age.

Case VIII (A. Karaman and H. Kahveci, 2010)

A male was born to unrelated parents aged 29 (father) and 25 (mother). On the day of birth, physical examination revealed:

  • Oligosyndactyly of the left foot
  • A short and angulated left leg

Radiographs revealed a short angulated tibia with fibular aplasia of the left leg. The left foot had only three metatarsal bones. Further examination also showed no abnormality of organs and no mutations in the WNT7A gene.

Case IX (Navendu Goyal, Randeep Kaur, Manu Gupta, Shiraz Bhatty and Rajesh Paul, 2014)

A 2 year old boy, born to healthy, presented with physical deformities:

  • Right foot with oligosyndactyly
  • Right lower limb was shorter than the left
  • Right foot was shorter than the left foot
  • No ankle, knee or hip

There was no physical deformities in the upper limbs or other parts of the body Radiographs showed hypoplastic fibula with hypoplasia of talus.

Case X (Gitte Smet, Yoeri Vankan and Annick Demeyere, 2016)

A female newborn, with no family history and healthy parents, presented with Hecht Scott syndrome. Physical examination revealed:

  • Three toes on the left foot
  • Four toes on the right foot
  • Shortening and bowing of the left lower limb of the tibia

There was no abnormality in the upper limbs and no facial dysmorphism. Hypoplasia of the left fibula was revealed by a radiographic examination. The radiograph also revealed the absence of two left rays and one ray on the right foot.

Case XI (Josko Petricevic, Ante Curic, Ivana Karaman, Gea Forempoher and Marija Definis-Gojanović, 2017)

A male baby was born prematurely due to fetal distress. Physical examination revealed:

  • A deformed tibia
  • Olygodactyly of both feet
  • Syndactyly of the right hand
  • Both fibulas were absent

A DNA analysis was conducted and no mutation was revealed on the WNT7A gene. Six days after birth, the baby died.