Hydrolethalus (Salonen-Herva-Norio) syndrome: further clinicopathological delineation

Reassessment of holoprosencephaly–diencephalic hamartoblastoma (HDH) association

We report on a 23-week fetus with a hypothalamic hamartoma, lobar holoprosencephaly, right anophthalmia, and facial asymmetry, features which are consistent with the holoprosencephaly-diencephalic hamartoblastoma (HDH) association. In an attempt to better delineate HDH, we reviewed 19 published patients with similar features. The HDH clinical spectrum ranges from classic holoprosencephaly with micro/anophthalmia, multiple additional findings in non-contiguous structures and early lethality, to isolated microforms of holoprosencephaly. Associated cephalic features mainly include cortical/neuronal migration defects (39%), meningeal anomalies (28%), brainstem/posterior fossa malformations (22%), dysmorphic ears (41%), facial asymmetry (35%), and hypoplastic mandible (29%). Fifty-three percent of patients have additional extra-cephalic malformations, for example, vertebral/rib segmentation defects (50%), hypo/aplastic lungs (38%), congenital heart defect (29%), and urinary anomalies (29%). HDH shows etiological heterogeneity, that is, teratogenic exposure, chromosome imbalances, autosomal recessive as well as dominant "de novo" mutations. Several features could directly result from a disruptive sequence caused by an early hamartoma which alters the development of forebrain, hindbrain, meninges, and 1st-2nd branchial arches, although the pleiotropic action of genetic/environmental factors cannot be excluded. HDH does not emerge as a distinct syndrome, but other hypotheses, including separate conditions within a common pathway and the developmental field defect theory, are discussed.

Hydrocephalus with cleft lip and palate: an overlap between midline malformation syndromes

We present a male infant with hydrocephalus, cleft lip/palate, micrognathia, club foot, laryngeal stenosis and ostium secundum type atrial septal defect. The karyotype was 46 XY. The combination of malformations observed overlaps with the characteristic findings of hydrolethalus syndrome, Meckel syndrome, Smith-Lemli-Opitz syndrome and pseudotrisomy 13. We discussed the differential diagnosis of the case.

An Asian girl with a 'milder' form of the Hydrolethalus syndrome

Hydrolethalus syndrome is an autosomal recessive disorder characterized by hydrocephalus, micrognathia, limb anomalies and several other abnormalities, mostly in the midline structures. The syndrome was first described in Finland, where the incidence is approximately 1 in 20000. All of the Finnish patients were stillborn or died during the first day of life. Only three non-Finnish cases have survived beyond the neonatal period. Here, we report the first Oriental girl with a 'milder' form of hydrolethalus syndrome. The patient died at age 44 days making her the fourth reported case surviving beyond the neonatal period. The case supports the concept of a 'milder' form of the syndrome. Whether this spectrum is due to allelism or locus heterogeneity awaits molecular analysis.

Hydrolethalus syndrome in a non-Finnish family: confirmation of the entity and early prenatal diagnosis

We present a family in which the first affected child presented with a 'milder' form of the hydrolethalus syndrome and survived to seven months, and two subsequent pregnancies with typical features detected early by ultrasound evaluation. We propose that the 'milder' cases are indeed true cases of the hydrolethalus syndrome and that allelic variability may be responsible for these 'non-typically Finnish' findings. We also demonstrate that, especially in families where there has been a previously affected fetus, echographic diagnosis can be made in the first trimester, as early as the 11th week of gestation.

Acrocallosal syndrome in an Algerian boy born to consanguineous parents: review of the literature and further delineation of the syndrome

We present a 17-month-old boy with the acrocallosal syndrome. He was born to consanguineous parents. Abnormal findings included agenesis of the corpus callosum, a ventricular septal defect (VSD), postaxial polydactyly of fingers, cleft soft palate, intestinal malrotation, large anterior fontanelle, prominent forehead, hypertelorism, epicanthic folds, short nose and mandible and preauricular skin tags, mixed hearing loss, laryngomalacia, and growth and severe motor and mental retardation. A review of previous reports on the acrocallosal syndrome shows considerable clinical variability; minimal diagnostic criteria are proposed. A developmental field defect with disturbance of midline development is suggested.

Dandy-Walker malformation and polydactyly: a possible expression of hydrolethalus syndrome

Hydrolethalus syndrome consists of hydrocephalus, polydactyly, micrognathia, midcranial malformations, visceral abnormalities and perinatal lethality. It was first described in Finland, and only a few other cases outside Scandinavia are known. We report the first Hungarian patient who displayed many signs of the syndrome but had no cleft lip and visceral abnormalities. This observation suggests the existence of oligosymptomic hydrolethalus syndrome, and suggests that Dandy-Walker malformation with polydactyly may be a manifestation of the hydrolethalus syndrome.

Prenatal ultrasound findings in hydrolethalus: continuing difficulties in diagnosis

We present the prenatal ultrasound findings in a case of hydrolethalus. This case illustrates ongoing problems in differentiating hydrolethalus, both pre- and postnatally, from other midline malformation syndromes including Pallister-Hall, Smith-Lemli-Opitz, pseudo-trisomy 13, oral facial-digital syndrome, and Meckel syndrome. Hydrolethalus can also be difficult to distinguish from certain skeletal dysplasias such as the short rib-polydactyly syndromes and campomelic dysplasia. Tests which can aid in diagnosis are presented.

Stringent delineation of Pallister-Hall syndrome in two long surviving patients: importance of radiological anomalies of the hands

We report two unrelated, long surviving patients (2 and 17 years) with syndromal hypothalamic hamartoblastoma. Both showed mild facial dysmorphism (downward slanted palpebral fissures, ptosis, microretrognathia), cleft epiglottis, and developmental delay. The younger child had stenosis of the pulmonary arteries, complex urogenital malformations, and anal atresia. In the oldest patient, the hamartoma caused precocious puberty of the central type, combined with complete hGH deficiency. Both patients showed bony anomalies of the extremities: variable proximal synostosis between central (2nd to 4th) metacarpals or intercalary polydactyly with generalised brachydactyly, severe brachytelephalangism, syndactyly, and nail hypoplasia. Together with the absence of anomalies of cholesterol metabolism, a combination of oral frenula, laryngeal malformations, digestive abnormalities, intercalary polysyndactyly, generalised brachytelephalangism, and nail hypoplasia should allow the delineation of Pallister-Hall syndrome, even when a CNS tumour is absent. The radiological abnormalities are helpful in differentiating Pallister-Hall syndrome from the other syndromes in which hypothalamic hamartoblastoma is observed. This is of major importance for genetic counselling, since Pallister-Hall syndrome may be a dominantly inherited disorder, thus contrasting with most of the other disorders with the CAVE phenotype, which are recessively inherited.

Multiple congenital malformations in two sibs reminiscent of hydrolethalus and pseudotrisomy 13 syndromes

We report on two sibs, born to consanguineous parents, with defects of the midline including cleft lip and palate, flat nose, hypotelorism, and dysgenesis of corpus callosum, in addition to short limbs, radiolucent tibial notch, digital anomalies, ambiguous genitalia, and hypopituitarism. In spite of the similarities between this condition and the hydrolethalus and pseudotrisomy 13 syndromes, our patients had neither preaxial nor postaxial polydactyly, but had previously undescribed bilateral radiolucent tibial notch, which is not known to be part of those two syndromes. The cases presented here may very well represent a new autosomal recessive syndrome.

Numerical syndromology: a mathematical approach to the nosology of complex phenotypes

Numerical taxonomy is defined by Sneath and Sokal as the grouping of taxonomic units on the basis of their character states by numerical methods of multivariate data analysis, and syndromology as the study of multiple congenital anomaly (MCA) syndromes and of their nosology. We present here an application of those methods to the analysis of overlapping syndromes. The main advantage of numerical taxonomy is that it allows simultaneous objective and unweighted analysis of multiple traits, giving the possibility to test mathematically the clinical hypotheses about the heterogeneity between closely resembling syndromes and uncovering objective patterns of anomalies, to be compared with the subjective pattern recognition process which characterizes most of the diagnostic approach in syndromology. In this paper, we explored 5 syndromes whose most severe expression belongs to the cerebroacrovisceral early lethality (CAVE) phenotype: hydrolethalus, severe Smith-Lemli-Opitz, orofaciodigital type VI (Varadi-Papp), holoprosencephaly-polydactyly, and Pallister-Hall syndromes. Fifty-five published cases, including many overlapping cases, were submitted to principal factor analysis followed by hierarchical clustering and graphical scaling. Results show that the 5 syndromes clearly constitute independent phenotypic entities, that some of the original diagnoses have to be reconsidered, and that many of the overlapping cases may be unambiguously set in one category. Hypothalamic hamartoblastoma appears to be a nonspecific dysplasia occurring in any of the 5 disorders.

Hypothalamic hamartoma in oral-facial-digital syndrome type VI (Váradi syndrome)

Oral-facial-digital syndrome (OFDS) type VI (Váradi syndrome) is an autosomal recessive trait of orofacial anomalies, cerebellar dysgenesis, and polysyndactyly. Developmental anomalies of the posterior fossa, including cerebellar hypoplasia and variants of the Dandy-Walker complex, are the most common central nervous system malformations reported in patients with this syndrome. We report hypothalamic hamartoma, supernumerary maxillary incisor, and precocious puberty in a boy with OFDS type VI. We propose that hypothalamic hamartoma is an occasional manifestation of OFDS type VI.

Familial Pallister-Hall syndrome: case report and hormonal evaluation

Pallister-Hall syndrome is a usually lethal dysplasia/malformation syndrome characterized by hypothalamic hamartoblastoma, hypopituitarism, postaxial polydactyly, craniofacial malformations, imperforate anus, and other malformations. We report a familial case in a male infant and his female sib fetus, suggesting autosomal recessive inheritance, or germinal mosaicism for an autosomal dominant mutation, or a segregating submicroscopic chromosome abnormality. Detailed endocrine evaluation on the surviving infant revealed documented pituitary function, pituitary deficit, and hypothalamic deficiency. We suggest that hypothalamic dysfunction contributes to the hypopituitarism seen in Pallister-Hall syndrome.

Two consecutive hydrolethalus syndrome-affected pregnancies in a nonconsanguinous black couple: discussion of problems in prenatal differential diagnosis of midline malformation syndromes

Hydrolethalus syndrome is a rare autosomal recessive (AR) disorder characterized by polyhydramnios, CNS abnormalities, cleft lip/palate, micrognathia, and polydactyly. Its molecular basis is unknown and prenatal diagnosis is challenging due to phenotypic overlap with several other midline malformation syndromes. A 34-year-old G3P2, nonconsanguinous, married, African-American woman was referred at 19 weeks of gestation after ultrasound findings of "multiple congenital anomalies." A previous pregnancy had been terminated following ultrasound findings of polyhydramnios, cleft lip/palate, polydactyly, severe hydrocephalus, and a Dandy-Walker malformation (DWM). Level II ultrasound evaluation of the current pregnancy demonstrated all of the anomalies which had been present in her previous pregnancy. Karyotype of amniocytes was 46,XX. Autopsy following pregnancy termination confirmed ultrasound findings. The pedigree, sonographic, and autopsy findings in this case were most consistent with hydrolethalus syndrome, although other AR multiple midline malformation syndromes were considered. Our case was detected by 19 weeks. Confident differential diagnosis is difficult for the geneticist and even more so for the sonologist given the technical limitations of ultrasound. It is uncertain whether these mendelian midline malformation syndromes represent slightly different phenotypic expressions of a common genetic defect or are manifestations of allelic and or locus heterogeneity. We suggest that for prenatal diagnostic purposes, in the absence of knowledge of the molecular basis of these disorders, the fine distinctions are not crucial as long as their mendelian inheritance is recognized and presence or absence of manifestations which make them severe are ascertained.

Overlap between Majewski and hydrolethalus syndromes: a report of two cases

We present 2 unrelated fetuses with manifestations of both the hydrolethalus syndrome and the short rib-polydactyly syndrome, type Majewski. It is proposed that cases of hydrolethalus syndrome with short limbs constitute a separate type of lethal osteochondrodysplasia mimicking short rib-polydactyly syndromes.

Variability versus heterogeneity in syndromal hypothalamic hamartoblastoma and related disorders: review and delineation of the cerebro-acro-visceral early lethality (CAVE) multiplex syndrome

We report on a case of neonatal hypothalamic hamartoblastoma with holoprosencephaly, Hirschsprung disease, and tetramelic postaxial polydactyly. Twenty-seven previous cases of congenital hypothalamic embryonic tumours with associated congenital defects are reviewed. A classification in isolated, associated, and syndromal forms is proposed. The difficulties encountered in differential diagnosis between the syndromal form (mainly represented by the Pallister-Hall syndrome) and related diseases as Smith-Lemli-Opitz type II, holoprosencephaly-polydactyly, orofaciodigital type VI and hydrolethalus syndromes are outlined. Two pathogenic mechanisms are discussed: a classical pleiotropic model and single sequence model. The latter is sufficient to delineate syndromal hypothalamic hamartoblastoma. With the former, syndromal hypothalamic hamartoblastoma cannot be clearly recognized in the absence of a CNS tumour, a child with syndromal hypothalamic hamartoblastoma cannot be reliably diagnosed as Pallister-Hall rather than another MCA syndrome, and, ultimately, the existence of Pallister-Hall syndrome could be questioned, as it could only be the extreme expression of one or several other syndromes. As this hypothesis cannot be proven or disproven at this point, the authors suggest creating the concept of multiplex phenotype. "Cerebro-Acro-Visceral Early lethality multiplex syndrome" is suggested to encompass all the ambiguous cases. Within this complex, an operative classification key is proposed.

Pallister-Hall syndrome associated with an unbalanced chromosome translocation

We report 3 cases of Pallister-Hall syndrome involving hypothalamic hamartoblastoma, hypopituitarism, cranial, and limb abnormalities. The first 2 cases represent the first apparent sibs reported with this syndrome. Patient 1 represents the first known patient with this syndrome with an abnormal karyotype.

On lumping and splitting: a fetus with clinical findings of the oral-facial-digital syndrome type VI, the hydrolethalus syndrome, and the Pallister-Hall syndrome

The three midline malformation complexes, the oral-facial-digital syndrome type VI (OFDS VI) or Váradi syndrome, the hydrolethalus syndrome (HS), and the Pallister-Hall syndrome (PHS) have been described as distinct genetic entities. Here, we report a fetus with a combination of clinical findings of all 3 syndromes similar to the twin fetuses described in the accompanying paper (Hingorani et al., 1991). The phenotypic overlap in these fetuses with the OFDS VI, HS, and PHS raises the question as to whether or not they indeed represent separate genetic entities as previously assumed.

Twin fetuses with abnormalities that overlap with three midline malformation complexes

Twin fetuses aborted at an estimated gestational age of 145 days were concordant for oral, facial, skeletal, and central nervous system malformations. The twins were discordant for other anomalies including cardiac defects, polydactyly, and malrotated short bowel. The combination of malformations observed overlaps with that of the oral-facial-digital syndrome, hydrolethalus syndrome, and Pallister-Hall syndrome. The problem of phenotypic overlap between these syndromes is discussed.

Fused eyelids, airway anomalies, ovarian cysts, and digital abnormalities in siblings: a new autosomal recessive syndrome or a variant of Fraser syndrome?

We describe two siblings of unlike gender born to non-consanguineous parents, with similar and unique congenital malformations. These include fused eyelids, craniofacial anomalies, ovarian cyst, subglottic stenosis, specific digital abnormalities, and no detected chromosomal abnormality. The specific digital abnormalities in both patients are characterized by extension of metacarpophalangeal joints with flexion of the proximal interphalangeal joint of both index fingers with resulting overlap of the second digit over the third. Similar changes were noted in both second toes. The brain weight of both infants was less than that expected for their birth weights. We reviewed the differential diagnosis of fused eyelids, airway anomalies, and ovarian cysts, and the manifestations resemble those seen in Fraser syndrome. We conclude that the dissimilarities warrant considering that our patients have a distinct autosomal recessive syndrome.

Holoprosencephaly-polydactyly ('pseudotrisomy 13') syndrome: a syndrome with features of hydrolethalus and Smith-Lemli-Opitz syndromes. A collaborative multicentre study

A syndrome of holoprosencephaly and postaxial polydactyly, associated with hydrocephalus, heart defect, adrenal hypoplasia, and other visceral malformations, has been observed in five unrelated children with normal chromosomes. Clinical overlap with lethal acrodysgenital dwarfism (Smith-Lemli-Opitz syndrome type II) and hydrolethalus syndrome is discussed. Recessive inheritance seems likely.

Hydrolethalus syndrome

Images

Holoprosencephaly and polydactyly: a possible expression of the hydrolethalus syndrome

We report two fetuses with hydrocephalus, features of holoprosencephaly, and postaxial polydactyly born to a consanguineous Mexican-American couple. The phenotype is consistent with the hydrolethalus syndrome, although holoprosencephaly has not previously been seen in this condition. We believe other similar cases with a trisomy 13 phenotype but normal chromosomes may also have the hydrolethalus syndrome.