Update on embryology of the upper limb.

Current concepts in the steps of upper limb development and the way the limb is patterned along its 3 spatial axes are reviewed. Finally, the embryogenesis of various congenital hand anomalies is delineated with an emphasis on the pathogenetic basis for each anomaly.

Sonographic identification of lower limb venous hypoplasia in the prenatal diagnosis of Klippel-Trénaunay syndrome.

We report the prenatal identification of lower-limb venous hypoplasia to support a provisional prenatal diagnosis of Klippel-Trénaunay syndrome (KTS). Ultrasound assessment of a fetus with marked lower-limb edema, cystic areas in the abdomen/pelvis/lower limbs and abnormal development of the feet demonstrated bilateral hypoplasia of the femoral and popliteal veins. The external iliac veins and the great saphenous veins were seen to be normal. The lower limb arterial system was present. These findings supported KTS as the most likely provisional diagnosis, and postnatal clinical evaluation confirmed that the infant is best classified in the spectrum of KTS. Venous hypoplasia was confirmed with a postnatal ultrasound examination of the lower limbs. This case suggests that careful examination of the lower-limb venous system may be helpful in making the prenatal diagnosis of KTS.

Rare case of fetal gastroschisis with aplasia of the foot and external genital organs.

Gastroschisis is a rare anomaly and is usually not associated with any other congenital anomalies. The embryology of gastroschisis and omphalocele remains a matter of speculation. Incidences of gastroschisis are particularly high among pregnancies in very young women. The present case is reported because of its rare association with the condition of gastroschisis, disrupted omphalocele, with aplasia of the foot and external genital organs, as well as imperforate anus with distal rectal atresia.

Regulation of Dlx5 and Dlx6 gene expression by p63 is involved in EEC and SHFM congenital limb defects.

The congenital malformation Split Hand-Foot Malformation (SHFM, or ectrodactyly) is characterized by a medial cleft of hands and feet, and missing central fingers. Five genetically distinct forms are known in humans; the most common (type-I) is linked to deletions of DSS1 and the distalless-related homeogenes DLX5 and DLX6. As Dlx5;Dlx6 double-knockout mice show a SHFM-like phenotype, the human orthologs are believed to be the disease genes. SHFM-IV and Ectrodactyly-Ectodermal dysplasia-Cleft lip (EEC) are caused by mutations in p63, an ectoderm-specific p53-related transcription factor. The similarity in the limb phenotype of different forms of SHFM may underlie the existence of a regulatory cascade involving the disease genes. Here, we show that p63 and Dlx proteins colocalize in the nuclei of the apical ectodermal ridge (AER). In homozygous p63- (null) and p63EEC (R279H) mutant limbs, the AER fails to stratify and the expression of four Dlx genes is strongly reduced; interestingly, the p63+/EEC and p63+/- hindlimbs, which develop normally and have a normally stratified AER, show reduced Dlx gene expression. The p63+/EEC mutation combined with an incomplete loss of Dlx5 and Dlx6 alleles leads to severe limb phenotypes, which are not observed in mice with either mutation alone. In vitro, DeltaNp63alpha induces transcription from the Dlx5 and Dlx6 promoters, an activity abolished by EEC and SHFM-IV mutations, but not by Ankyloblepharon-Ectodermal defects-Cleft lip/palate (AEC) mutations. ChIP analysis shows that p63 is directly associated with the Dlx5 and Dlx6 promoters. Thus, our data strongly implicate p63 and the Dlx5-Dlx6 locus in a pathway relevant in the aetio-pathogenesis of SHFM.

Abnormal urethra formation in mouse models of split-hand/split-foot malformation type 1 and type 4.

Urogenital birth defects are one of the common phenotypes observed in hereditary human disorders. In particular, limb malformations are often associated with urogenital developmental abnormalities, as the case for Hand-foot-genital syndrome displaying similar hypoplasia/agenesis of limbs and external genitalia. Split-hand/split-foot malformation (SHFM) is a syndromic limb disorder affecting the central rays of the autopod with median clefts of the hands and feet, missing central fingers and often fusion of the remaining ones. SHFM type 1 (SHFM1) is linked to genomic deletions or rearrangements, which includes the distal-less-related homeogenes DLX5 and DLX6 as well as DSS1. SHFM type 4 (SHFM4) is associated with mutations in p63, which encodes a p53-related transcription factor. To understand that SHFM is associated with urogenital birth defects, we performed gene expression analysis and gene knockout mouse model analyses. We show here that Dlx5, Dlx6, p63 and Bmp7, one of the p63 downstream candidate genes, are all expressed in the developing urethral plate (UP) and that targeted inactivation of these genes in the mouse results in UP defects leading to abnormal urethra formation. These results suggested that different set of transcription factors and growth factor genes play similar developmental functions during embryonic urethra formation. Human SHFM syndromes display multiple phenotypes with variations in addition to split hand foot limb phenotype. These results suggest that different genes associated with human SHFM could also be involved in the aetiogenesis of hypospadias pointing toward a common molecular origin of these congenital malformations.

The windblown hand - diagnosis, clinical picture and pathogenesis.

The syndrome of the windblown hand deformity is a complex constellation of malformations affecting not only the head and the feet but also the hands in a quite distinct manner. In the hand, it involves congenital bilateral flexion contracture with ulnar deviation of the metacarpophalangeal joints. The thumb is characteristically adducted (reaching the palm; "thumb-in-palm deformity") with flexion of the MP joint and hyperextension of the IP joint. The etiology is basically unknown. We present two theories based on knowledge derived from the disciplines of evolution biology and embryology. We believe that the atavistic appearance of phylogenetically primitive muscle groups in conjunction with an impaired rotation of the extremities during embryological development account for this malformation syndrome.

Evaluation of femur/foot and humerus/foot ratios by transvaginal sonography between 62 and 116 days of gestation.

OBJECTIVE: The objective was to construct nomograms of femur/foot length and humerus/foot length ratios in early pregnancy by transvaginal sonography. METHODS: In the period 1994-2000, 1,008 singleton pregnant patients were examined from 62 to 116 days of gestation using transvaginal high-resolution ultrasound technique. As a part of biometric survey femur, humerus and foot length were recorded and evaluated as ratio at each gestational age. The distribution of the residuals for the different ratios is also described. RESULTS: A significant correlation was demonstrated between femur and foot length (R2=0.984; p<0.0001) and between humerus and foot length (R2=0.983; p<0.0001). The femur/foot length and humerus foot/length ratios were approximately 1 throughout this period of gestation with a narrow range. CONCLUSION: The presented data obtained in early pregnancy by transvaginal scan offer normative measurements of femur/foot length and humerus foot/length ratios which may be useful in the prenatal diagnosis of congenital syndromes that include skeletal maldevelopment.

An autopsy case of Adams-Oliver syndrome.

We report an autopsy case of a male fetus with Adams-Oliver syndrome. His mother was a healthy, 31-year-old woman and her family and past histories were unremarkable. Therapeutic termination was done at 28(+6) weeks gestational age due to oligohydramnios detected by antenatal ultrasonography. Chromosomal study revealed normal karyotype. On autopsy, characteristic transverse terminal defect of four extremities was found. Both feet were short and broad. All toes were rudimentary with no nails and fingers were irregularly short. On infantogram, all toe-bones were stubby and rudimentary. The middle and terminal phalanges of 2nd, 3rd & 5th fingers and the terminal phalange of 4th finger on the right hand were absent. The middle and terminal phalanges of 2nd & 5th fingers and terminal phalange of 3rd finger were defected on the left hand. His abnormalities were consistent with features of Adams-Oliver syndrome, which has not been reported in Korea.

Anatomy of a duplicated human foot from a limb with fibular dimelia.

At birth, a patient presented with a right lower limb featuring preaxial polydactyly and fibular dimelia with a complete absence of the tibia. Radiographic studies of the patient's foot revealed a duplicated tarsus with eight metatarsals and toes. The three preaxial toes were surgically removed at 1 year of age. A hallux and four normal-appearing postaxial toes remained. The foot was amputated when the patient was 3 years old. Dissection of the amputated foot revealed that the muscles of the dorsum were normal, except that the tendon of the extensor hallucis brevis muscle inserted into both the hallux and toe 2, rather than only into the hallux. The few abnormalities observed among the muscles on the plantar surface of the foot included absence of the insertions of the tibialis posterior and the abductor hallucis muscles. In addition, the two heads of the adductor hallucis muscle inserted abnormally into the medial (tibial) side of metatarsal 1, rather than into the lateral side. These various muscular anomalies, in addition to the mirror duplication of the foot with the presence of only a single metatarsal 1, leads us to propose that this metatarsal probably represents two lateral (fibular) halves that form a laterally duplicated bone. Although the dorsalis pedis artery was present on the dorsal surface of the foot, most of its derivatives were absent. This artery did give rise to a supernumerary medial branch that ended abruptly in the connective tissue (presumably postsurgical scar) at the medial border of the foot. This branch may have represented a duplicated dorsalis pedis artery associated with the duplicated preaxial portion of the foot. The arteries on the plantar surface of the foot were normal. Even though some anomalies in the pattern of the cutaneous innervation were observed, the nerves of the foot were largely normal. The gross and radiographic anatomy of this specimen and the radiographic anatomy of the leg suggest that some teratogenic event occurred when developmental specification reached the level of the future knee. The teratogenic event, which probably occurred early in the fifth week of development, may have caused damage that led to a lateral duplication of both the leg and the foot with the absence of some of the most medial structures. Teratology 60:272-282, 1999.

A new spontaneous mouse mutation of Hoxd13 with a polyalanine expansion and phenotype similar to human synpolydactyly.

Human synpolydactyly (SPD) is an inherited congenital limb malformation caused by mutations in the HOXD13 gene. Heterozygotes are typically characterized by 3/4 finger and 4/5 toe syndactyly with associated duplicated digits; hands and feet of homozygotes are very small because of a shortening of the phalanges, metacarpal and metatarsal bones. Here we describe the phenotype and molecular basis of a spontaneous mutation of Hoxd13 in mice that provides a phenotypically and molecularly accurate model for human SPD. The new mutation, named synpolydactyly homolog (spdh), is a 21 bp in-frame duplication within a polyalanine-encoding region at the 5'-end of the Hoxd13 coding sequence. The duplication expands the stretch of alanines from 15 to 22; the same type of expansion occurs in human SPD mutations. spdh/spdh homozygotes exhibit severe malformations of all four feet, including polydactyly, syndactyly and brachydactylia. The phenotype of spdh is much more severe than that exhibited by mice with a genetically engineered, presumably null, disruption of Hoxd13. Thus spdh probably acts in a dominant-negative manner and will be valuable for examining interactions with other Hox genes and their protein products during limb development. Homozygous mice of both sexes also lack preputial glands and males do not breed; therefore, spdh/spdh mice may also be valuable in studies of reproductive physiology and behavior.

Severe malformation of one foot from amniocentesis needle injury.

An 11-year-old boy is described who was born with a poorly developed right foot. At 16 weeks gestation his mother had had amniocentesis without direct ultrasound guidance. After the insertion of the amniocentesis needle, she felt strong abdominal resistance, which disappeared with slight withdrawal of the needle. Then, real-time ultrasound was used to determine the position of the needle, which was reported to be up against the feet. Nine days later deep purple amniotic fluid was removed by amniocentesis. At birth there was a scab over an oozing hole in the lateral aspect of his right 'foot', a poorly formed structure with five digit-like structures at the tip. It seems most likely that the deformity was caused by tissue injury from needle puncture at 16 weeks gestation.

Full monosomy 21, prenatally diagnosed by fluorescent in situ hybridization.

We describe a case of full monosomy 21 which was prenatally diagnosed in chorionic villi by fluorescent in situ hybridization (FISH). Because of intrauterine fetal death, a curettage was performed and cytogenetic analysis of skin fibroblasts confirmed the presence of monosomy 21 in fetal cells. DNA investigations showed a paternal origin of the single chromosome 21. Inspection and autopsy of the fetus revealed several congenital malformations. Some of them have been reported in earlier studies of monosomy 21; others concern new observations. Regarding the eye, the following abnormalities were microscopically observed: absence of the anterior and posterior eye chambers, aniridy, a hypoplastic ciliary body, Peter's anomaly, and a double retina with secondary dysplasia. In addition, malformations of the extremities were seen: partial, proximal syndactyly of digits 3 and 4 of the right hand; pes varus position of the right foot; and transverse reduction defect at the tarsals of the left foot. To our knowledge, this is the first case in which full monosomy 21 has been proven.

Cystic hygroma as an early first-trimester ultrasound marker for recurrent Fryns' syndrome.

We present a case of a fetus who at a 12-week ultrasound examination was shown to have a large cystic hygroma. Fryns' syndrome was suspected because the mother's previous pregnancy had been affected by the condition. Pathological examination confirmed the diagnosis at this early stage of gestation. In families with increased risk for Fryns' syndrome, first-trimester ultrasound screening should be offered to exclude cystic hygroma as an ultrasound marker for this most often lethal malformation.

Congenital scalp defect, distal limb reduction anomalies, right spastic hemiplegia and hypoplasia of the left arteria cerebri media. Further evidence that interruption of early embryonic blood supply may result in Adams-Oliver (plus) syndrome.

In this report we describe a male patient with the interesting combination of a large congenital scalp defect, distal limb reduction anomalies, right spastic hemiplegia and hypoplasia of the left arteria cerebri media. Follow-up data from birth up to the age of 18 years revealed positive evolution with low to normal intelligence. The findings in the present patient, i.e. an Adams-Oliver syndrome associated with a severe neurological deficit, are best explained as resulting from interruption of the early embryonic blood supply.

Mirror image duplication of the hands and feet: report of a sporadic case with multiple congenital anomalies.

Mirror image duplication of the hands and feet is a rare entity. Based on 3 previous reports, findings include nasal abnormalities, dimelia of ulna and fibula, tibial hypoplasia and mirror image duplication of hands and feet. We report on a sporadic case in which mirror image duplication was associated with multiple congenital anomalies. Although these cases may represent variable expression of the same dominantly transmitted complex polysyndactyly syndrome, it is possible that mirror image duplication of the hands and feet is a manifestation common to a number of distinct clinical entities. During limb bud development, duplication and aberrant positioning of the zone of polarizing activity in relation to the apical ectodermal ridge may account for the anatomic abnormalities of the hands and feet in these patients.

Symmetrical terminal transverse limb defects: report of a twenty-week fetus.

A 20-week gestation hydropic Thai fetus is reported who had symmetrical absence of each hand and forefoot with persistence of digit-like nubbins on each limb. The histologic studies showed there was calcified acellular material in the digit-like nubbins, consistent with infarcted blood vessels, and cartilaginous structures that represented possibly the distal metacarpal articulating surface. The red blood cell indices of both parents were consistent with their being heterozygous for a hemoglobinopathy, such as alpha-thalassemia, which is common in Thais. The infarcted blood vessels could be the result of thrombosis of the digital arteries in the fetus due to a hemoglobinopathy such as hemoglobin Bart's, just as rabbit fetuses homozygous for brachydactyly have transverse terminal digit amputations following digital vessel occlusions due to macrocytic anemia. This was the only child with symmetrical absence of the hands and feet identified among 123,489 liveborn and stillborn infants surveyed for major malformations.

[Congenital round talus]. / Der angeborene runde Talus.

The collective consists of 11 patients with a "ball and socket"-anomaly of the talus with a mean age of 13.7 years. All patients demonstrated typical symptoms of the FFU-syndrome with a leg length discrepancy of 4.3 cm (2-20). In 6 patients a close follow-up was done in the early development of the talus form. In the metacarpal region also synostosis of some bones were seen at a mean age of 4.8 years (3.2-5.9). No clinical complaints but a slight reduction of hind foot mobility could been registered. Ball and socket deformity can not been seen as congenital, but as a subsequent deformity after congenital fusions in the metatarsal bones.