The natural history of a genetic subtype of arrhythmogenic right ventricular cardiomyopathy caused by a p.S358L mutation in TMEM43.

To determine the phenotype and natural history of a founder genetic subtype of autosomal dominant arrhythmogenic right ventricular cardiomyopathy (ARVC) caused by a p.S358L mutation in TMEM43. The age of onset of cardiac symptoms, clinical events and test abnormalities were studied in 412 subjects (258 affected and 154 unaffected), all of which occurred in affected males significantly earlier and more often than unaffected males. Affected males were hospitalized four times more often than affected females (p ≤ 0.0001) and died younger (p ≤ 0.001). The temporal sequence from symptoms onset to death was prolonged in affected females by 1-2 decades. The most prevalent electrocardiogram (ECG) manifestation was poor R wave progression (PRWP), with affected males twice as likely to develop PRWP as affected females (p ≤ 0.05). Left ventricular enlargement (LVE) occurred in 43% of affected subjects, with 11% fulfilling criteria for dilated cardiomyopathy. Ventricular ectopy on Holter monitor was common and occurred early: the most diagnostically useful clinical test. No symptom or test could rule out diagnosis. This ARVC subtype is a sex-influenced lethal arrhythmogenic cardiomyopathy, with a unique ECG finding, LV dilatation, heart failure and early death, where molecular pre-symptomatic diagnosis has the greatest clinical utility.

Premature death in adults with 22q11.2 deletion syndrome.

BACKGROUND: 22q11.2 deletion syndrome (22q11.2DS) is a multisystem disease with a prevalence of 1/4000. Variable expression of congenital and later onset features contributes to its under-recognition. Longevity in those surviving childhood is believed to be normal but data are limited. METHODS: We prospectively followed 264 subjects; 102 adults (>17 years) with 22q11.2DS (44 male (M), 58 female (F); mean (SD) age 33.6 (10.9) years) and their 162 unaffected siblings (77 M, 85 F; mean age 36.1 (12.2) years). We compared survival between groups using Kaplan-Meier estimates. RESULTS: Twelve (11.8%; 4 M, 8 F) individuals with 22q11.2DS and no siblings died (p<0.0001). Survival to ages 40 and 50 years was 89.9% and 73.9%, respectively. Median age at death was 41.5 (range 18.1-68.6) years. Deaths included two (7.7%) of 26 subjects with neither major congenital heart disease (CHD) nor schizophrenia. Four of six sudden and unexpected deaths occurred in individuals with no major CHD. There was no evidence of cancer or coronary artery disease or family history of sudden death in the 12 patients who died, six of whom had autopsies. DISCUSSION: Individuals with 22q11.2DS who survive childhood have diminished life expectancy and increased risk of sudden death not attributable to any single factor. Some sudden and/or premature deaths observed in the general population may represent undiagnosed 22q11.2DS. Increased recognition of the syndrome by family doctors, specialists and coroners will be essential to facilitate the tissue studies needed to determine underlying mechanisms.

Elevated rates of schizophrenia in a familial sample with mental illness and intellectual disability.

BACKGROUND: It is unknown whether intellectual disability (ID) is more familially related to psychotic mood disorders or schizophrenia. L. S. Penrose's large sample of families with two or more members admitted to psychiatric hospitals provided a unique opportunity to investigate the familial relationship between mild ID, schizophrenia and psychotic affective disorders. METHOD: There were 183 affected relative pairs comprising probands with mild ID (95 male, 88 female) and their first or second degree relatives with schizophrenia or psychotic affective disorder. RESULTS: There were nearly twice as many relatives with a diagnosis of schizophrenia (n = 121) as relatives with affective disorders (n = 62) among the intellectually impaired probands. This excess of schizophrenia was statistically significant, even after accounting for the increased risk of hospitalization for schizophrenia (P = 0.005), and was fairly constant across the different relative types. First-degree relatives with either mental illness were more likely to be parents (n = 77) than siblings (n = 51) or children (n = 3), but there was no excess of mother-son pairs. CONCLUSIONS: These results suggest a stronger familial relationship of ID with schizophrenia than psychotic affective disorder, and lend some support to the neurodevelopmental hypothesis of schizophrenia.

Genetic counselling for schizophrenia in the era of molecular genetics.

OBJECTIVE: To review the role of genetic counselling for individuals with psychiatric illnesses. METHOD: Using schizophrenia as an example and including updated information about a genetic subtype (22q deletion syndrome), we discuss the value of the genetic counselling process in psychiatry, with support from the literature and our clinical experience. RESULTS: Genetic counselling, the process through which knowledge about the genetics of illnesses is shared, provides information on the inheritance of illnesses and their recurrence risks; addresses the concerns of patients, their families, and their health care providers; and supports patients and their families dealing with these illnesses. For comprehensive medical management, this service should be available to all individuals with schizophrenia and their families. CONCLUSIONS: New findings in the genetics of psychiatric illness may have important clinical implications for patients and their families.

Location of a major susceptibility locus for familial schizophrenia on chromosome 1q21-q22.

Schizophrenia is a complex disorder, and there is substantial evidence supporting a genetic etiology. Despite this, prior attempts to localize susceptibility loci have produced predominantly suggestive findings. A genome-wide scan for schizophrenia susceptibility loci in 22 extended families with high rates of schizophrenia provided highly significant evidence of linkage to chromosome 1 (1q21-q22), with a maximum heterogeneity logarithm of the likelihood of linkage (lod) score of 6.50. This linkage result should provide sufficient power to allow the positional cloning of the underlying susceptibility gene.

Reproductive fitness in familial schizophrenia.

BACKGROUND: Reproductive fitness is an important factor in understanding inheritance in genetic disorders. The purpose of this study was to determine whether fitness is reduced in familial schizophrenia (FS) and if fitness in siblings differs from the norm. METHOD: The number of offspring in 36 subjects with RDC schizophrenia or schizoaffective disorder (SZ) and their 101 siblings from large FS families was compared with age-adjusted census figures. RESULTS: Fitness in the SZ group was significantly reduced: 23% of expected in males and 51% of expected in females. Fitness of unaffected siblings was within census expectations. However, female siblings with schizophrenia spectrum features had increased fitness over census norms. Reduced fitness was correlated with low marital rates, poor functioning and positive symptoms. CONCLUSIONS: These results indicate that reduced fitness is an important genetic force in FS and is likely inherent to the illness. Sex differences are important and would need to be considered when examining maternal and paternal transmission of schizophrenia. The results support a proposed high mutation rate for schizophrenia, consistent with a dynamic mutation mechanism.

Diagnosis of adult polycystic kidney disease by genetic markers and ultrasonographic imaging in a voluntary family register.

Diagnosis of autosomal dominant adult polycystic kidney disease (APKD) is possible by ultrasonographic scanning (USS) or by using DNA markers linked to the PKD1 locus. Ultrasonography is complicated by the age dependent penetrance of the gene and linkage studies are subject to recombination errors owing to meiotic crossing over and locus heterogeneity. This study draws on data collected from a voluntary family register of APKD over 10 years. Records of 150 families were examined, ultrasound reports were obtained from 242 people at 50% prior risk, and 37 families were typed for DNA markers. The fraction of APKD resulting from loci unlinked to PKD1 (designated PKD2 here) was calculated at 2.94% (upper confidence limit 8.62%). Some subjects who were negative on initial scan later gave a positive scan, but there was no example of a definite gene carrier aged over 30 giving a negative scan. In families large enough for linkage analysis, most people who were at 50% prior risk could be given a final risk below 5% or above 95%, by using combined ultrasound and DNA studies.

Acrania: a manifestation of the Adams-Oliver syndrome.

A 10-year-old male with acrania, distal limb anomalies, and abnormal arterial and venous cranial blood vessels is reported. Parental films and examination are normal. This case supports the hypothesis that acrania is a severe form of aplasia cutis congenita and is within the spectrum of Adams-Oliver syndrome. It is proposed that the diagnosis of acrania requires assessment of both parents and proband to assess other manifestations of vascular disruption in order to provide accurate genetic counselling.

King syndrome: a genetically heterogenous phenotype due to congenital myopathies.

We report on a patient with myopathy, kyphoscoliosis, joint contractures, and a facial appearance consistent with King syndrome. Unlike other reported cases, our patient had hyperextensible joints, normal stature, and pectus excavatum. The cardiac ventricles, aorta, and pulmonary artery were dilated. Malignant hyperthermia did not occur under anaesthesia although there was a transient increase in CK levels. Muscle bulk and tone were significantly decreased but collagen and elastin fibres were normal. The variable clinical presentation of King syndrome suggests that the manifestations are caused by different congenital myopathies and in all cases there is probably an increased risk of malignant hyperthermia.

Branchio-oto-renal syndrome: further delineation of an underdiagnosed syndrome.

We report on a woman who was diagnosed with branchio-oto-renal (BOR) syndrome after 2 pregnancies complicated by oligohydramnios due to renal hypoplasia and agenesis. Both babies died neonatally of pulmonary hypoplasia. Histopathology of the temporal bones of the second child showed marked immaturity of the middle ear cleft, ossicles, facial nerve and canal, and cochlear nerve. Maternal renal ultrasound study was normal although intravenous pyelography indicated renal hypoplasia. The frequency of BOR syndrome among cases of recurrent fetal renal hypoplasia/dysplasia or agenesis is unknown, and parental renal ultrasonography may not identify a heritable renal defect. Investigations should include a family history, and examination of relatives to look for preauricular pits, lacrimal duct stenosis, and branchial fistulae and/or cysts. Hearing studies and IVP may be indicated.

Intrafamilial variability in cleidocranial dysplasia: a three generation family.

We present a 3-generation family, ascertained after the birth of a child with cleidocranial dysplasia (CCD). The propositus presented with respiratory distress (due to a narrow thorax) and hypoplasia and discontinuity of both clavicles. The mother, aunt, and grandmother had varied features of the condition. This intrafamilial variation illustrates the need for clinical assessment of family members following the birth of an apparent sporadic case of CCD.

Mucolipidosis type IV: clinical manifestations and natural history.

The clinical manifestations and psychomotor development of five patients with mucolipidosis IV (MLIV) from three Ashkenazi-Jewish families are reported. The presenting symptoms were hypotonia, developmental delay, corneal clouding, and puffy eyelids. Four of the patients had convergent strabismus and none progressed beyond a developmental age of 15 months. One patient died of aspiration at 17 years while the oldest patient entered puberty at 20 years, developed a coarse face at 30 years, and is now 32 years old. Histopathological studies in four patients showed storage changes characteristic of MLIV.

Syndrome of mental retardation and distal arthrogryposis in sibs.

Two sisters presented with a syndrome of characteristic facial anomalies and distal arthrogryposis. The older sister is now 4 years old and is severely mentally retarded. Her sister died of respiratory failure due to hypoplastic lungs shortly after birth. The occurrence of this potentially lethal syndrome in 2 sisters with unaffected parents suggests autosomal recessive inheritance.

Robin sequence with facial and digital anomalies in two half-brothers by the same mother.

Two half-brothers by the same mother presented with the Robin sequence and facial and digital anomalies. The mother has a normal face and mild hyperopia without abnormality on radiographs of the hands, feet, and pelvis. The older son is 4 years and the younger is 6 months old. Both have normal psychomotor development. To the best of our knowledge this familial association has not been reported before and probably represents a previously unrecognized heritable malformation syndrome. The occurrence of the syndrome in 2 half-brothers by the same unaffected mother suggests X-linked recessive inheritance.

Adult polycystic kidney disease: knowledge, experience, and attitudes to prenatal diagnosis.

One hundred and ninety subjects from 100 adult polycystic kidney disease (APKD) families on the North Western Regional Genetic Register were interviewed to determine the likely demand for prenatal diagnosis. A detailed questionnaire was used to assess understanding and experience of clinical, therapeutic, and genetic aspects of APKD. Major features of the disease (presence of renal cysts which can lead to renal failure) and forms of therapy (dialysis and transplantation) were known; knowledge of less common features was related to experience. The cohort had had genetic counselling and the majority knew the risk to their own offspring, although the mechanics of the mode of inheritance was often misunderstood. Uptake of presymptomatic ultrasound testing was high, and some implications of early diagnosis are noted. A minority changed their reproductive behaviour as a result of APKD, and although the majority felt a prenatal test should be available, only 23% at high risk of passing on the disease and contemplating children felt they would be interested, and so far only one request for prenatal diagnosis has been received. Thus, demand appears to be low and to be related to perception of the seriousness of APKD.

Recombination or heterogeneity: is there a second locus for adult polycystic kidney disease?

Twenty-four families with adult onset polycystic kidney disease were typed for markers flanking the PKD1 locus on chromosome 16. The aggregated results gave a significant lod score in favour of linkage to PKD1. Within this group of families two showed unusual features: recombinations, including double recombinations, and, in one family, an unexpectedly high proportion of affected people. We consider the evidence that in these families the disease might result from a mutation at a different locus, PKD2, not linked to PKD1. We suggest that a useful test is to compare the relative numbers of meioses apparently non-recombinant and doubly recombinant for markers flanking the normal disease locus, ignoring meioses recombinant for only a single marker. Using this test, neither our two families nor the data published so far on other families provide compelling evidence for the existence of a second locus for adult polycystic kidney disease. For genetic counselling in families too small to give internal evidence for or against linkage, the extra uncertainty can be handled by using a higher recombination rate.