Syndrome of tetraamelia with pulmonary hypoplasia

A review of supernumerary and absent limbs and digits of the upper limb

For years people have been enamored by anomalies of the human limbs, particularly supernumerary and absent limbs and digits. Historically, there are a number of examples of such anomalies, including royal families of ancient Chaldea, tribes from Arabia, and examples from across nineteenth century Europe. The development of the upper limbs in a growing embryo is still being elucidated with the recent advent of homeobox genes, but researchers agree that upper limbs develop between stages 12-23 through a complex embryological process. Maternal thalidomide intake during limb development is known to cause limb reduction and subsequent amelia or phocomelia. Additionally, a number of clinical reports have illustrated different limb anomaly cases, with each situation unique in phenotype and developmental abnormality. Supernumerary and absent limbs and digits are not unique to humans, and a number of animal cases have also been reported. This review of the literature illustrates the historical, anatomical, and clinical aspects of supernumerary and absent limbs and digits for the upper limb.

Homozygous WNT3 mutation causes tetra-amelia in a large consanguineous family

Tetra-amelia is a rare human genetic disorder characterized by complete absence of all four limbs and other anomalies. We studied a consanguineous family with four affected fetuses displaying autosomal recessive tetra-amelia and craniofacial and urogenital defects. By homozygosity mapping, the disease locus was assigned to chromosome 17q21, with a maximum multipoint LOD score of 2.9 at markers D17S931, D17S1785, D17SS1827, and D17S1868. Further fine mapping defined a critical interval of approximately 8.9 Mb between D17S1299 and D17S797. We identified a homozygous nonsense mutation (Q83X) in the WNT3 gene in affected fetuses of the family. WNT3, a human homologue of the Drosophila wingless gene, encodes a member of the WNT family known to play key roles in embryonic development. The Q83X mutation truncates WNT3 at its amino terminus, suggesting that loss of function is the most likely cause of the disorder. Our findings contrast with the observation of early lethality in mice homozygous for null alleles of Wnt3. To our knowledge, this is the first report of a mutation in a WNT gene associated with a Mendelian disorder. The identification of a WNT3 mutation in tetra-amelia indicates that WNT3 is required at the earliest stages of human limb formation and for craniofacial and urogenital development.

Molecular basis of autosomal recessive diseases among the Palestinian Arabs

In the review of the literature, 71 different autosomal recessive diseases have been delineated that are relatively frequent among Palestinian Arabs. Among those, in 40 the mutation(s) responsible for the diseases are known. Fourteen of these disorders were caused by a single mutation, while the other 26 were due to multiple mutations. Most of the mutations were found in homozygosity among the affected patients. It is probable that the high frequency of most of the genetic diseases among the Palestinian Arabs is due to a founder effect as the result of the high consanguinity rates in this population. However, in some cases the high frequency was demonstrated to be secondary to the presence of multiple mutations, either allelic or in different genes in a small geographic region. This phenomenon remains unexplained but may be secondary to a selective advantage to the carriers, either specific to the region or to the population.

Roberts syndrome, normal cell division, and normal intelligence

Roberts-SC phocomelia syndrome (RS) is an autosomal recessive disorder of symmetric limb defects, craniofacial abnormalities, pre- and postnatal growth retardation, and mental retardation. Patients with RS have been reported to have premature separation of heterochromatin of many chromosomes and abnormalities in the cell-division cycle. No case has been reported who had normal intelligence and normal cell division with typical clinical features of the RS. We report a case of a six-year-old male of clinical and radiologic findings of typical RS with normal cell division and normal intelligence. Although he showed growth retardation, his intelligence was normal. Van Den Berg and Francke later reported that 79 out of 100 cases of Roberts syndrome had premature cell separation (PCS). We think that this case may demonstrate severe expression of the Roberts syndrome even though PCS is not exhibited. The limb involvement of this case was symmetrical, and he showed phocomelia of upper limbs, equinus valgus deformity of ankle, aplasia of fibula, and shortness of fifth toes while his hands and feet were normal with 5 rays each. Craniofacial abnormalities of this case were typical; he showed scaphocephaly, mild hypertelorism, mandibular hypoplasia, dysplastic helix of ear, narrowing of external auditory canal, and cleft palate with wide gap. This report supports the theory that normal intelligence can make social-personal adjustment possible even if all of the stigmata of Roberts syndrome is present.

[Pulmonary hypoplasia in adults: embryology, clinical presentation and diagnostic methods. Our experience and review of the literature]

We report five patients diagnosed of pulmonary hypoplasia (PH) in adulthood (age > 18 years, range 45 to 67 years). PH was left-sided in four cases. The malformations found were 2 cases of renal agenesis, 2 diaphragmatic hernias and 1 hiatal hernia. Lung function data were FEV1 0.88 +/- 0.32 L; FVC 1.30 +/- 0.52 L; FEV 1/FVC 68.5 +/- 5%. Arterial gases (with FiO2 0.21) were PaO2 63.6 +/- 24 and PaCO2 47.1 +/- 11.2 mmHg. Three cases were referred for monitoring of respiratory insufficiency (2 requiring home oxygen therapy) and two for radiographic study of chest disease. The diagnoses were made by computerized tomography (CT) of the chest. Congenital diseases due to underdeveloped lungs in the pseudoglandular phase are rarely diagnosed in adults (48 cases, including ours, have been found in the literature), and PH is rarely diagnosed, possibly because the anomalies observed are attributed to old infections. Clinical presentation is highly variable, depending in large measure on a history of smoking and repeated respiratory infections. Chest CT is at present the diagnostic tool of choice.

Tetra-amelia and splenogonadal fusion in Roberts syndrome

Roberts-SC phocomelia syndrome comprises limb deficiencies of variable severity, facial clefts, and other anomalies. Tetra-amelia may also be associated with facial clefts and similar anomalies. We report on a female infant with severe tetra-amelia, micrognathia, cleft palate, splenogonadal fusion, and premature centromere separation. We propose that this represents the severe expression of the Roberts-SC phocomelia syndrome.

Zimmer phocomelia: delineation by principal coordinate analysis

We present a 46,XX stillborn fetus with tetraphocomelia, absence of ears, severe hypoplasia of nose, cleft palate, pulmonary hypoplasia, imperforate anus and vagina, and phallus-like structure on an otherwise undefined perineum. The pattern of abnormalities resembles the tetraphocomelic condition described by Zimmer et al. in 1985. Tetraphocomelia, ear/nose hypoplasia with facial clefts, pulmonary hypoplasia, and defects of the caudal end including imperforate anus, and abnormal genitalia constitute a distinct pattern of malformation termed Zimmer phocomelia. Principal coordinate analysis with Gower's similarity index supported the clinical impression that cases reported by Zimmer and the present case are distinct from other phocomelic conditions. Although Zimmer phocomelia is currently referred to as "X-linked amelia," documentation of a female case with a penis-like structure in this report as well as consanguinity in the original family in Zimmer's report indicates that this condition is likely inherited in an autosomal recessive fashion. Zimmer phocomelia may be a more appropriate name than X-linked amelia.

New autosomal recessive form of amelia

Amelia is a rare, usually sporadic malformation. We report on a family in which three fetuses had amelia of the upper limbs and variable deficiency of the lower limbs. The fetuses also had minor facial anomalies. Recurrence of the condition in sibs of both sexes suggests autosomal recessive inheritance. Recurrent amelia has been documented in only a few families most often associated with a different set of malformations. Possibly, mutations in more than one gene with different modes of transmission can lead to this severe limb deficiency. We speculate that the mutation found in our cases interferes with formation of the apical ectodermal ridge in the upper limbs and results in its premature degeneration in the lower limbs.