Riyadh chromosome breakage syndrome: mental retardation with depigmentation of the skin and hair

Radiotherapy and genetic predisposition to breast cancer

Cancer genetics is becoming increasingly integrated into oncological care; particularly in breast cancer management. The recognition of monogenic breast cancer predisposition syndromes, such as BRCA, is critical as there is also a risk of other cancers in addition to a markedly elevated risk of contralateral breast cancer. In individuals with breast cancer due to some predisposition genes, radiation should be avoided, e.g. the ATM and TP53 genes, but there is still controversy as to whether radiation should be used in BRCA1/2 mutation carriers and more follow-up is needed. There are some radiation-sensitive genetic conditions where, if breast cancer occurs (as it may occur in any individual, not necessarily due to an increased risk associated with the condition), radiation should be avoided. These conditions are often associated with dysmorphic features. If such features are noticed then the advice of a geneticist should be sought urgently prior to giving radiation.

Human herpesvirus-6 (HHV-6)-associated necrotizing encephalitis in Griscelli's syndrome

We report a male caucasian German pediatric patient of no Arab or Mediterranean ancestry with virus associated CNS lesions in Griscelli's syndrome (GS; McKusick No. 214450). The boy presented with recurrent infections, and meningitis with subsequent progressive signs of increased intracranial pressure leading to death at 32 weeks of age. At autopsy, various sites of the CNS revealed necroses in gray and white matter. CNS histology revealed numerous and massive predominantly perivascular CD8 positive lymphohistiocytic infiltrates. These findings were associated strictly with the presence of human herpesvirus-6 (HHV-6) genome or the HHV-6 specific late antigen H-AR 3, found in neurons, oligodendrocytes, and astrocytes. The search for HHV-6 replication dependent antigen, HHV-7 DNA, CMV, adenovirus, Coxsackie B1, B2, and B4-antigens, and mycobacteria was not successful. Detection of viruses was attempted using immunohistochemistry, in situ hybridization or nested polymerase chain reaction, respectively. Lymphocyte typing was carried out immunohistochemically. In GS, virus induced CNS damage does not seem to require necessarily active virus replication. It may also appear as a consequence of an immune reaction triggered by antigen expression.

Partial albinism with immunodeficiency (Griscelli syndrome)

Partial albinism with immunodeficiency is a rare and fatal immunologic disorder characterized by pigmentary dilution and variable cellular immunodeficiency. To define the phenotype, therapy, and outcome, we retrospectively analyzed seven consecutive patients. Primary abnormalities included a silvery-grayish sheen to the hair, large pigment agglomerations in hair shafts, and an abundance of mature melanosomes in melanocytes, with reduced pigmentation of adjacent keratinocytes. Clinical onset occurred between the ages of 4 months and 4 years and was characterized by accelerated phases (lymphohistiocytic infiltration of multiple organs, including the brain and the meninges), triggered by viral and bacterial infections. Characteristic laboratory features included pancytopenia, hypofibrinogenemia, hypertriglyceridemia, and hypoproteinemia. Consistent immunologic abnormalities were characterized by absent delayed-type cutaneous hypersensitivity and impaired natural killer cell function. Some patients had secondary hypogammaglobulinemia, impaired major histocompatibility complex-mediated cytotoxic effects, a decreased capacity of lymphocytes to trigger a mixed lymphocyte reaction, or various functional granulocytic abnormalities. The disease seems to be invariably lethal without bone marrow transplantation; the mean age at the time of death was 5 years. Bone marrow transplantation has been performed in three cases; two patients died in the immediate posttransplantation period of infectious complications, but one patient is cured after a follow-up of 5 years. We conclude that partial albinism with immunodeficiency (Griscelli syndrome) can be differentiated from Chédiak-Higashi syndrome by pathognomonic histologic features. One of the underlying immunologic defects may be a defective function of natural killer cells, predisposing the patient to virus-associated hemophagocytic syndrome or accelerated phases. The prognosis is very poor unless early bone marrow transplantation is carried out.

Neurometabolic diseases at a national referral center: five years experience at the King Faisal Specialist Hospital and Research Centre

Of 910 children under the age of 12 years referred to the national center, we were able to assign an etiology to 473 (52%). This group consisted of lysosomal storage diseases (32%), amino acid disorders (14%), organic acid disorders (16%), various chromosome abnormalities and syndromes with dysmorphia or brain dysgenesis (26%), and various other metabolic diseases (12%). While such amino acidemias as branched-chain amino acidemia (MSUD) in classic and intermediate forms (44%) and hyperphenylalaninemia (PKU) due to 6-pyruvoyltetrahydropterin synthase deficiency (6PTSD) (19%) were common, classic PKU was rare (16%). Methylmalonic acidemia (31%), 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency (16%), and propionic acidemia (12%) were encountered more frequently than other types of organic acidemias. When compared to the number of referred Down's syndrome patients, the results suggested the birth of at least one infant with neurometabolic disease per 50 births. Five tribes of Saudi Arabia constituted 26% of the diagnosable neurometabolic diseases. Diseases such as MSUD, 6 PTSD, Sanfilippo syndrome type B, methylmalonic acidemia, homocystinuria, GM2 gangliosidosis Sandhoff variant, infantile central nervous system spongy degeneration (Canavan disease), and neuraminidase deficiency showed definite tribal occurrence. In addition, 32% to 42% of the definitely diagnosed, and 25% to 87% of patients with probable neurometabolic disease but without a definable etiology, had more than one sibling affected. It is concluded that the many rare autosomal diseases of Saudi Arabia are due to "founder effect" created by marriages occurring within tribal and extended family boundaries.